diff --git a/backend/app/api/routes/scan.py b/backend/app/api/routes/scan.py
index 1b3fd06..2b778d2 100644
--- a/backend/app/api/routes/scan.py
+++ b/backend/app/api/routes/scan.py
@@ -15,8 +15,12 @@ from app.db.database import AsyncSessionLocal, get_db
 from app.db.models import Design, Edge, Node, PendingDevice, PendingDeviceLink, ScanRun
 from app.schemas.nodes import NodeCreate
 from app.schemas.scan import PendingDeviceResponse, ScanRunResponse
+from app.services.node_dedupe import dedupe_nodes_by_ieee
 from app.services.scanner import DeepScanOptions, _valid_port_range, request_cancel, run_scan
-from app.services.zigbee_service import build_zigbee_properties
+from app.services.zigbee_service import (
+    build_zigbee_properties,
+    merge_zigbee_properties,
+)
 from app.services.zwave_service import build_zwave_properties
 
 _ZIGBEE_TYPES = {"zigbee_coordinator", "zigbee_router", "zigbee_enddevice"}
@@ -308,6 +312,9 @@ async def bulk_approve_devices(
     db: AsyncSession = Depends(get_db),
     _: str = Depends(get_current_user),
 ) -> dict[str, Any]:
+    # Repair any legacy same-canvas duplicate nodes before placing more.
+    await dedupe_nodes_by_ieee(db)
+
     # Target the design the user is on; fall back to the first design.
     default_design_id = payload.design_id
     if default_design_id is None:
@@ -469,6 +476,35 @@ async def approve_device(
         raise HTTPException(status_code=409, detail="Device already processed")
     device.status = "approved"
     wireless = _is_wireless(node_data.type)
+
+    # Guard against a true duplicate: same IEEE already placed on THIS design.
+    # (The same device on a *different* design is valid — one Node per canvas.)
+    if device.ieee_address is not None:
+        dup = (
+            await db.execute(
+                select(Node).where(
+                    Node.ieee_address == device.ieee_address,
+                    Node.design_id == node_design_id,
+                )
+            )
+        ).scalars().first()
+        if dup is not None:
+            dup.properties = merge_zigbee_properties(
+                dup.properties,
+                _wireless_properties(
+                    node_data.type, device.ieee_address,
+                    device.vendor, device.model, device.lqi,
+                ) if wireless else [],
+            )
+            edges = await _resolve_pending_links_for_ieee(db, device.ieee_address)
+            await db.commit()
+            return {
+                "approved": True,
+                "node_id": dup.id,
+                "edges_created": len(edges),
+                "edges": edges,
+            }
+
     # Prefer the MAC discovered during the scan (stored on the pending device);
     # fall back to whatever the approve payload carried.
     _mac = device.mac or node_data.mac
diff --git a/backend/app/api/routes/zigbee.py b/backend/app/api/routes/zigbee.py
index 9e69af1..dd62039 100644
--- a/backend/app/api/routes/zigbee.py
+++ b/backend/app/api/routes/zigbee.py
@@ -23,6 +23,7 @@ from app.schemas.zigbee import (
     ZigbeeTestConnectionRequest,
     ZigbeeTestConnectionResponse,
 )
+from app.services.node_dedupe import dedupe_nodes_by_ieee
 from app.services.zigbee_service import (
     build_zigbee_properties,
     fetch_networkmap,
@@ -138,6 +139,10 @@ async def _persist_pending_import(
     Coordinator auto-approves to a canvas Node. Other devices upsert by IEEE.
     All zigbee-source links are wiped and re-inserted from the new map.
     """
+    # Repair any pre-existing duplicate nodes (same IEEE) before upserting, so
+    # the by-IEEE lookups below resolve to a single row.
+    await dedupe_nodes_by_ieee(db)
+
     # Determine target design (use first design as fallback)
     first_design = (await db.execute(select(Design).order_by(Design.created_at).limit(1))).scalar()
     default_design_id = first_design.id if first_design else None
@@ -156,15 +161,22 @@ async def _persist_pending_import(
         )
 
         if n.get("device_type") == "Coordinator":
-            existing = await db.execute(select(Node).where(Node.ieee_address == ieee))
-            existing_node = existing.scalar_one_or_none()
-            if existing_node:
-                existing_node.properties = merge_zigbee_properties(
-                    existing_node.properties, props
+            # The coordinator may sit on several canvases (one Node per design).
+            # Refresh props on every matching node, not just one.
+            existing_nodes = (
+                await db.execute(
+                    select(Node).where(Node.ieee_address == ieee).order_by(Node.id)
                 )
+            ).scalars().all()
+            if existing_nodes:
+                for existing_node in existing_nodes:
+                    existing_node.properties = merge_zigbee_properties(
+                        existing_node.properties, props
+                    )
+                first = existing_nodes[0]
                 coordinator_out = ZigbeeCoordinatorOut(
-                    id=existing_node.id,
-                    label=existing_node.label,
+                    id=first.id,
+                    label=first.label,
                     ieee_address=ieee,
                 )
                 coordinator_existed = True
@@ -188,16 +200,18 @@ async def _persist_pending_import(
             continue
 
         # If the device has already been approved as a canvas Node, refresh
-        # its properties and skip creating a pending row (keeps approved
-        # devices out of pending/hidden modals on re-import).
-        existing_node_q = await db.execute(
-            select(Node).where(Node.ieee_address == ieee)
-        )
-        existing_node = existing_node_q.scalar_one_or_none()
-        if existing_node:
-            existing_node.properties = merge_zigbee_properties(
-                existing_node.properties, props
+        # its properties on every canvas it sits on and skip creating a pending
+        # row (keeps approved devices out of pending/hidden modals on re-import).
+        existing_nodes = (
+            await db.execute(
+                select(Node).where(Node.ieee_address == ieee).order_by(Node.id)
             )
+        ).scalars().all()
+        if existing_nodes:
+            for existing_node in existing_nodes:
+                existing_node.properties = merge_zigbee_properties(
+                    existing_node.properties, props
+                )
             continue
 
         result = await db.execute(
diff --git a/backend/app/api/routes/zwave.py b/backend/app/api/routes/zwave.py
index 241dc38..56fc355 100644
--- a/backend/app/api/routes/zwave.py
+++ b/backend/app/api/routes/zwave.py
@@ -23,6 +23,7 @@ from app.schemas.zwave import (
     ZwaveTestConnectionRequest,
     ZwaveTestConnectionResponse,
 )
+from app.services.node_dedupe import dedupe_nodes_by_ieee
 from app.services.zwave_service import (
     build_zwave_properties,
     fetch_zwave_network,
@@ -134,6 +135,10 @@ async def _persist_pending_import(
     Coordinator auto-approves to a canvas Node. Other devices upsert by Z-Wave
     identity. All zwave-source links are wiped and re-inserted from the new map.
     """
+    # Repair any pre-existing same-canvas duplicate nodes before upserting, so
+    # the by-IEEE lookups below resolve cleanly.
+    await dedupe_nodes_by_ieee(db)
+
     first_design = (await db.execute(select(Design).order_by(Design.created_at).limit(1))).scalar()
     default_design_id = first_design.id if first_design else None
 
@@ -149,15 +154,22 @@ async def _persist_pending_import(
         props = build_zwave_properties(ieee, n.get("vendor"), n.get("model"))
 
         if n.get("type") == "zwave_coordinator":
-            existing = await db.execute(select(Node).where(Node.ieee_address == ieee))
-            existing_node = existing.scalar_one_or_none()
-            if existing_node:
-                existing_node.properties = merge_zwave_properties(
-                    existing_node.properties, props
+            # The coordinator may sit on several canvases (one Node per design).
+            # Refresh props on every matching node, not just one.
+            existing_nodes = (
+                await db.execute(
+                    select(Node).where(Node.ieee_address == ieee).order_by(Node.id)
                 )
+            ).scalars().all()
+            if existing_nodes:
+                for existing_node in existing_nodes:
+                    existing_node.properties = merge_zwave_properties(
+                        existing_node.properties, props
+                    )
+                first = existing_nodes[0]
                 coordinator_out = ZwaveCoordinatorOut(
-                    id=existing_node.id,
-                    label=existing_node.label,
+                    id=first.id,
+                    label=first.label,
                     ieee_address=ieee,
                 )
                 coordinator_existed = True
@@ -180,15 +192,18 @@ async def _persist_pending_import(
             )
             continue
 
-        # Already approved as a canvas Node → refresh props, skip pending row.
-        existing_node_q = await db.execute(
-            select(Node).where(Node.ieee_address == ieee)
-        )
-        existing_node = existing_node_q.scalar_one_or_none()
-        if existing_node:
-            existing_node.properties = merge_zwave_properties(
-                existing_node.properties, props
+        # Already approved as a canvas Node → refresh props on every canvas it
+        # sits on, skip pending row.
+        existing_nodes = (
+            await db.execute(
+                select(Node).where(Node.ieee_address == ieee).order_by(Node.id)
             )
+        ).scalars().all()
+        if existing_nodes:
+            for existing_node in existing_nodes:
+                existing_node.properties = merge_zwave_properties(
+                    existing_node.properties, props
+                )
             continue
 
         result = await db.execute(
diff --git a/backend/app/services/node_dedupe.py b/backend/app/services/node_dedupe.py
new file mode 100644
index 0000000..76fa1cd
--- /dev/null
+++ b/backend/app/services/node_dedupe.py
@@ -0,0 +1,161 @@
+"""Collapse *true* duplicate canvas nodes: same ``ieee_address`` **and** same
+``design_id`` (i.e. the same device placed twice on the *same* canvas).
+
+The same device legitimately appears on multiple canvases — placing a device on
+another design creates a second :class:`Node` for that IEEE by design (see the
+per-design guard in ``bulk_approve_devices``). Those cross-design rows are NOT
+duplicates and must be preserved. Only two rows sharing both the IEEE *and* the
+design are corrupt, and only those are collapsed here.
+
+This module provides an idempotent, **loss-free** repair: per ``(ieee,
+design_id)`` group with >1 node it keeps the oldest as canonical, merges the
+extras' data into it (properties, missing scalar fields, services), re-points
+every edge and ``parent_id`` reference onto the canonical node, then deletes the
+extras. Edges are de-duplicated and self-loops dropped after re-pointing so no
+dangling or redundant links remain.
+"""
+
+from __future__ import annotations
+
+import logging
+from typing import Any
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.db.models import Edge, Node
+from app.services.zigbee_service import merge_zigbee_properties
+
+logger = logging.getLogger(__name__)
+
+# Scalar Node fields worth carrying over from a duplicate when the canonical
+# node has no value. Positions, design, parent and identity fields are left on
+# the canonical node untouched (that's the row the user actually placed).
+_FILLABLE_FIELDS = (
+    "hostname",
+    "ip",
+    "mac",
+    "os",
+    "check_method",
+    "check_target",
+    "notes",
+    "cpu_count",
+    "cpu_model",
+    "ram_gb",
+    "disk_gb",
+    "custom_icon",
+    "last_seen",
+    "last_scan",
+)
+
+
+def _merge_services(
+    a: list[Any] | None, b: list[Any] | None
+) -> list[Any]:
+    """Union two service lists, de-duplicated, order-stable."""
+    out: list[Any] = list(a or [])
+    seen = {repr(s) for s in out}
+    for s in b or []:
+        if repr(s) not in seen:
+            out.append(s)
+            seen.add(repr(s))
+    return out
+
+
+def _merge_into_canonical(canonical: Node, dup: Node) -> None:
+    """Fold ``dup``'s data into ``canonical`` in place (no field lost)."""
+    canonical.properties = merge_zigbee_properties(
+        canonical.properties, dup.properties or []
+    )
+    canonical.services = _merge_services(canonical.services, dup.services)
+    for field in _FILLABLE_FIELDS:
+        if getattr(canonical, field, None) in (None, "") and getattr(dup, field, None) not in (None, ""):
+            setattr(canonical, field, getattr(dup, field))
+    # Prefer a human label over a bare IEEE/hex fallback.
+    if (not canonical.label or canonical.label == canonical.ieee_address) and dup.label:
+        canonical.label = dup.label
+
+
+async def dedupe_nodes_by_ieee(db: AsyncSession) -> int:
+    """Merge duplicate nodes sharing an ``ieee_address`` AND ``design_id``.
+
+    Returns the number of nodes removed. Idempotent: a no-op when every
+    ``(ieee, design)`` pair maps to at most one node. Nodes with the same IEEE
+    on *different* designs are left untouched (valid cross-canvas placement).
+    Does not commit — the caller owns the transaction.
+    """
+    rows = (
+        await db.execute(
+            select(Node)
+            .where(Node.ieee_address.is_not(None))
+            .order_by(Node.ieee_address, Node.created_at, Node.id)
+        )
+    ).scalars().all()
+
+    groups: dict[tuple[str, str | None], list[Node]] = {}
+    for node in rows:
+        groups.setdefault((node.ieee_address, node.design_id), []).append(node)  # type: ignore[arg-type]
+
+    removed = 0
+    for (ieee, _design), nodes in groups.items():
+        if len(nodes) < 2:
+            continue
+        canonical, *dups = nodes  # oldest first (ordered above)
+        dup_ids = {d.id for d in dups}
+
+        for dup in dups:
+            _merge_into_canonical(canonical, dup)
+
+        # Re-point edges + parents, then drop self-loops / duplicates.
+        edges = (
+            await db.execute(
+                select(Edge).where(
+                    Edge.source.in_(dup_ids) | Edge.target.in_(dup_ids)
+                )
+            )
+        ).scalars().all()
+        for edge in edges:
+            if edge.source in dup_ids:
+                edge.source = canonical.id
+            if edge.target in dup_ids:
+                edge.target = canonical.id
+
+        # Re-point children whose parent was a duplicate.
+        children = (
+            await db.execute(select(Node).where(Node.parent_id.in_(dup_ids)))
+        ).scalars().all()
+        for child in children:
+            child.parent_id = canonical.id
+
+        # Collapse self-loops and now-redundant parallel edges.
+        all_edges = (
+            await db.execute(
+                select(Edge).where(
+                    (Edge.source == canonical.id) | (Edge.target == canonical.id)
+                )
+            )
+        ).scalars().all()
+        seen_pairs: set[tuple[str, str, str]] = set()
+        for edge in all_edges:
+            if edge.source == edge.target:
+                await db.delete(edge)
+                continue
+            key = (edge.source, edge.target, edge.type)
+            if key in seen_pairs:
+                await db.delete(edge)
+                continue
+            seen_pairs.add(key)
+
+        await db.flush()
+        for dup in dups:
+            await db.delete(dup)
+            removed += 1
+
+        logger.info(
+            "Deduped IEEE %s: merged %d duplicate node(s) into %s",
+            ieee, len(dups), canonical.id,
+        )
+
+    if removed:
+        await db.flush()
+    return removed
diff --git a/backend/tests/test_node_dedupe.py b/backend/tests/test_node_dedupe.py
new file mode 100644
index 0000000..be702f1
--- /dev/null
+++ b/backend/tests/test_node_dedupe.py
@@ -0,0 +1,117 @@
+"""Tests for the same-canvas node dedupe repair (app.services.node_dedupe)."""
+
+import pytest
+from sqlalchemy import select
+
+from app.db.models import Design, Edge, Node
+from app.services.node_dedupe import dedupe_nodes_by_ieee
+
+
+async def _design(db, name="d1"):
+    d = Design(name=name)
+    db.add(d)
+    await db.flush()
+    return d
+
+
+@pytest.mark.asyncio
+async def test_collapses_same_ieee_same_design(db_session):
+    d = await _design(db_session)
+    keep = Node(
+        label="Sensor", type="zigbee_enddevice", design_id=d.id,
+        ieee_address="0xAAA", properties=[{"key": "IEEE", "value": "0xAAA", "visible": True}],
+        pos_x=100, pos_y=200,
+    )
+    db_session.add(keep)
+    await db_session.flush()
+    dup = Node(
+        label="Sensor", type="zigbee_enddevice", design_id=d.id,
+        ieee_address="0xAAA", ip="10.0.0.5",
+        properties=[{"key": "LQI", "value": "88", "visible": False}],
+    )
+    db_session.add(dup)
+    await db_session.flush()
+
+    removed = await dedupe_nodes_by_ieee(db_session)
+    assert removed == 1
+
+    nodes = (await db_session.execute(select(Node).where(Node.ieee_address == "0xAAA"))).scalars().all()
+    assert len(nodes) == 1
+    survivor = nodes[0]
+    assert survivor.id == keep.id          # oldest kept
+    assert survivor.pos_x == 100           # canvas position preserved
+    assert survivor.ip == "10.0.0.5"       # missing field filled from dup
+    keys = {p["key"] for p in survivor.properties}
+    assert keys == {"IEEE", "LQI"}         # properties merged
+
+
+@pytest.mark.asyncio
+async def test_preserves_same_ieee_across_designs(db_session):
+    """Same device on two canvases is valid — must NOT be merged."""
+    d1 = await _design(db_session, "d1")
+    d2 = await _design(db_session, "d2")
+    for d in (d1, d2):
+        db_session.add(Node(label="S", type="zigbee_enddevice", design_id=d.id, ieee_address="0xBBB"))
+    await db_session.flush()
+
+    removed = await dedupe_nodes_by_ieee(db_session)
+    assert removed == 0
+
+    nodes = (await db_session.execute(select(Node).where(Node.ieee_address == "0xBBB"))).scalars().all()
+    assert len(nodes) == 2
+
+
+@pytest.mark.asyncio
+async def test_repoints_edges_and_drops_dupes(db_session):
+    d = await _design(db_session)
+    keep = Node(label="A", type="server", design_id=d.id, ieee_address="0xCCC")
+    dup = Node(label="A", type="server", design_id=d.id, ieee_address="0xCCC")
+    other = Node(label="B", type="server", design_id=d.id)
+    db_session.add_all([keep, other])
+    await db_session.flush()
+    db_session.add(dup)
+    await db_session.flush()
+
+    # keep<->other and dup<->other (parallel after repoint), plus dup<->keep (self-loop).
+    db_session.add_all([
+        Edge(source=keep.id, target=other.id, type="ethernet", design_id=d.id),
+        Edge(source=dup.id, target=other.id, type="ethernet", design_id=d.id),
+        Edge(source=dup.id, target=keep.id, type="ethernet", design_id=d.id),
+    ])
+    await db_session.flush()
+
+    removed = await dedupe_nodes_by_ieee(db_session)
+    assert removed == 1
+
+    edges = (await db_session.execute(select(Edge))).scalars().all()
+    # self-loop dropped, parallel edge collapsed -> a single keep<->other edge
+    assert len(edges) == 1
+    e = edges[0]
+    assert {e.source, e.target} == {keep.id, other.id}
+
+
+@pytest.mark.asyncio
+async def test_repoints_child_parent(db_session):
+    d = await _design(db_session)
+    keep = Node(label="Host", type="proxmox", design_id=d.id, ieee_address="0xDDD")
+    dup = Node(label="Host", type="proxmox", design_id=d.id, ieee_address="0xDDD")
+    db_session.add(keep)
+    await db_session.flush()
+    db_session.add(dup)
+    await db_session.flush()
+    child = Node(label="VM", type="vm", design_id=d.id, parent_id=dup.id)
+    db_session.add(child)
+    await db_session.flush()
+
+    await dedupe_nodes_by_ieee(db_session)
+    await db_session.refresh(child)
+    assert child.parent_id == keep.id
+
+
+@pytest.mark.asyncio
+async def test_idempotent_noop_when_unique(db_session):
+    d = await _design(db_session)
+    db_session.add(Node(label="X", type="server", design_id=d.id, ieee_address="0xEEE"))
+    await db_session.flush()
+    assert await dedupe_nodes_by_ieee(db_session) == 0
+    assert await dedupe_nodes_by_ieee(db_session) == 0
diff --git a/backend/tests/test_scan.py b/backend/tests/test_scan.py
index 2114bb1..8087e20 100644
--- a/backend/tests/test_scan.py
+++ b/backend/tests/test_scan.py
@@ -311,6 +311,44 @@ async def test_approve_device(client: AsyncClient, headers, pending_device):
     assert inventory[0]["status"] == "approved"
 
 
+@pytest.mark.asyncio
+async def test_approve_device_no_dupe_same_ieee_same_design(
+    client: AsyncClient, headers, db_session
+):
+    """Approving a device whose IEEE is already on the target design must reuse
+    the existing node, not create a duplicate (source of the crash bug)."""
+    design = Design(name="d1")
+    db_session.add(design)
+    await db_session.flush()
+    existing = Node(
+        label="sensor", type="zigbee_enddevice", ieee_address="0xZZZ",
+        services=[], design_id=design.id,
+    )
+    db_session.add(existing)
+    device = PendingDevice(
+        id=str(uuid.uuid4()), ieee_address="0xZZZ", suggested_type="zigbee_enddevice",
+        status="pending", discovery_source="zigbee",
+    )
+    db_session.add(device)
+    await db_session.commit()
+
+    res = await client.post(
+        f"/api/v1/scan/pending/{device.id}/approve",
+        json={
+            "label": "sensor", "type": "zigbee_enddevice",
+            "status": "online", "services": [], "design_id": design.id,
+        },
+        headers=headers,
+    )
+    assert res.status_code == 200
+    assert res.json()["node_id"] == existing.id  # reused, not new
+
+    nodes = (
+        await db_session.execute(select(Node).where(Node.ieee_address == "0xZZZ"))
+    ).scalars().all()
+    assert len(nodes) == 1  # no duplicate created
+
+
 @pytest.mark.asyncio
 async def test_approve_nonexistent_device(client: AsyncClient, headers):
     node_payload = {
diff --git a/backend/tests/test_zigbee_router.py b/backend/tests/test_zigbee_router.py
index 5096531..7467f15 100644
--- a/backend/tests/test_zigbee_router.py
+++ b/backend/tests/test_zigbee_router.py
@@ -618,6 +618,43 @@ async def test_persist_pending_import_refreshes_existing_coordinator_properties(
     assert by_key["Model"]["visible"] is False
 
 
+@pytest.mark.asyncio
+async def test_persist_pending_import_device_on_multiple_canvases(
+    db_session,
+) -> None:
+    """Regression: a device approved onto TWO designs (one Node each) must not
+    crash re-import with MultipleResultsFound — props refresh on both nodes."""
+    from sqlalchemy import select
+
+    from app.api.routes.zigbee import _persist_pending_import
+    from app.db.models import Design, Node
+
+    d1 = Design(name="d1")
+    d2 = Design(name="d2")
+    db_session.add_all([d1, d2])
+    await db_session.flush()
+    for d in (d1, d2):
+        db_session.add(Node(
+            label="router_1", type="zigbee_router", status="online",
+            check_method="none", ieee_address="0xR1", services=[],
+            properties=[], design_id=d.id,
+        ))
+    await db_session.commit()
+
+    bumped = [dict(n) for n in _PENDING_NODES]
+    bumped[1]["lqi"] = 240
+    # Must not raise.
+    await _persist_pending_import(db_session, bumped, _PENDING_EDGES)
+
+    nodes = (
+        await db_session.execute(select(Node).where(Node.ieee_address == "0xR1"))
+    ).scalars().all()
+    assert len(nodes) == 2  # both canvas placements preserved
+    for n in nodes:
+        lqi = {p["key"]: p["value"] for p in n.properties}.get("LQI")
+        assert lqi == "240"  # refreshed on every canvas
+
+
 @pytest.mark.asyncio
 async def test_import_pending_requires_auth(client: AsyncClient) -> None:
     res = await client.post(
diff --git a/backend/tests/test_zwave_router.py b/backend/tests/test_zwave_router.py
index 6974738..3aa7130 100644
--- a/backend/tests/test_zwave_router.py
+++ b/backend/tests/test_zwave_router.py
@@ -445,3 +445,38 @@ async def test_persist_keeps_hidden_hidden(db_session) -> None:
         )
     ).scalar_one()
     assert still_hidden.status == "hidden"
+
+
+@pytest.mark.asyncio
+async def test_persist_device_on_multiple_canvases(db_session) -> None:
+    """Regression: a device on TWO designs (one Node each) must not crash
+    re-import with MultipleResultsFound — props refresh on both nodes."""
+    from sqlalchemy import select
+
+    from app.api.routes.zwave import _persist_pending_import
+    from app.db.models import Design, Node
+
+    d1 = Design(name="d1")
+    d2 = Design(name="d2")
+    db_session.add_all([d1, d2])
+    await db_session.flush()
+    for d in (d1, d2):
+        db_session.add(Node(
+            label="Wall Plug", type="zwave_router", status="online",
+            check_method="none", ieee_address="zwave-0xh-2", services=[],
+            properties=[], design_id=d.id,
+        ))
+    await db_session.commit()
+
+    bumped = [dict(n) for n in _PENDING_NODES]
+    bumped[1]["model"] = "ZW200"
+    # Must not raise.
+    await _persist_pending_import(db_session, bumped, _PENDING_EDGES)
+
+    nodes = (
+        await db_session.execute(select(Node).where(Node.ieee_address == "zwave-0xh-2"))
+    ).scalars().all()
+    assert len(nodes) == 2  # both canvas placements preserved
+    for n in nodes:
+        model = {p["key"]: p["value"] for p in n.properties}.get("Model")
+        assert model == "ZW200"  # refreshed on every canvas