diff --git a/weed/topology/duplicate_volume_id_test.go b/weed/topology/duplicate_volume_id_test.go
index 79d498409c..42cb6fd97a 100644
--- a/weed/topology/duplicate_volume_id_test.go
+++ b/weed/topology/duplicate_volume_id_test.go
@@ -133,3 +133,55 @@ func TestQuarantineSurvivesResync(t *testing.T) {
 		t.Fatal("resync must not clear the quarantine")
 	}
 }
+
+func TestReplicationChangeIsNotDuplicate(t *testing.T) {
+	topo := NewTopology("topo", nil, 128, 3, false)
+	rpOld, _ := super_block.NewReplicaPlacementFromString("000")
+	rpNew, _ := super_block.NewReplicaPlacementFromString("001")
+
+	dn1 := NewDataNode("server1")
+	dn1.Ip = "10.0.0.1"
+	dn1.Port = 8080
+	dn2 := NewDataNode("server2")
+	dn2.Ip = "10.0.0.2"
+	dn2.Port = 8080
+
+	vOld := storage.VolumeInfo{Id: 7, Collection: "a", ReplicaPlacement: rpOld, Ttl: needle.EMPTY_TTL}
+	vNew := storage.VolumeInfo{Id: 7, Collection: "a", ReplicaPlacement: rpNew, Ttl: needle.EMPTY_TTL}
+
+	dn1.UpdateVolumes([]storage.VolumeInfo{vOld})
+	dn2.UpdateVolumes([]storage.VolumeInfo{vNew})
+	topo.RegisterVolumeLayout(vOld, dn1)
+	topo.RegisterVolumeLayout(vNew, dn2)
+	topo.flagDuplicateVolumeId(vNew, dn2)
+
+	if topo.isQuarantined(dn2, vNew.Id) || topo.isQuarantined(dn1, vOld.Id) {
+		t.Fatal("an rp-only layout difference is a replication change in flight, not a duplicate")
+	}
+}
+
+func TestDuplicateVolumeIdAcrossTtls(t *testing.T) {
+	topo := NewTopology("topo", nil, 128, 3, false)
+	rp, _ := super_block.NewReplicaPlacementFromString("000")
+	ttl, _ := needle.ReadTTL("3d")
+
+	dn1 := NewDataNode("server1")
+	dn1.Ip = "10.0.0.1"
+	dn1.Port = 8080
+	dn2 := NewDataNode("server2")
+	dn2.Ip = "10.0.0.2"
+	dn2.Port = 8080
+
+	v1 := storage.VolumeInfo{Id: 7, Collection: "a", ReplicaPlacement: rp, Ttl: needle.EMPTY_TTL}
+	v2 := storage.VolumeInfo{Id: 7, Collection: "a", ReplicaPlacement: rp, Ttl: ttl}
+
+	dn1.UpdateVolumes([]storage.VolumeInfo{v1})
+	dn2.UpdateVolumes([]storage.VolumeInfo{v2})
+	topo.RegisterVolumeLayout(v1, dn1)
+	topo.RegisterVolumeLayout(v2, dn2)
+	topo.flagDuplicateVolumeId(v2, dn2)
+
+	if !topo.isQuarantined(dn2, v2.Id) || !topo.isQuarantined(dn1, v1.Id) {
+		t.Fatal("same collection with a different ttl is still a reused volume id")
+	}
+}
diff --git a/weed/topology/topology.go b/weed/topology/topology.go
index e4e49cc5f3..3c68d3586b 100644
--- a/weed/topology/topology.go
+++ b/weed/topology/topology.go
@@ -790,6 +790,13 @@ func volumeLayoutKey(collection string, rp *super_block.ReplicaPlacement, ttl *n
 	return fmt.Sprintf("collection=%q rp=%s ttl=%s disk=%s", collection, rp, ttl, diskType)
 }
 
+func ttlEqual(a, b *needle.TTL) bool {
+	if a == nil || b == nil {
+		return a == b
+	}
+	return a.ToUint32() == b.ToUint32()
+}
+
 
 // findDuplicateVolumeLayouts reports every layout that already holds v.Id on
 // data nodes other than dn. Volume ids are global, so the same id held by two
@@ -802,12 +809,12 @@ func (t *Topology) findDuplicateVolumeLayouts(v storage.VolumeInfo, dn *DataNode
 	var hits []duplicateHit
 	for _, item := range t.collectionMap.Items() {
 		c := item.(*Collection)
-		var same *VolumeLayout
-		if c.Name == v.Collection {
-			same, _ = c.GetVolumeLayout(v.ReplicaPlacement, v.Ttl, diskType)
-		}
 		for _, vl := range c.GetAllVolumeLayouts() {
-			if vl == same {
+			if c.Name == v.Collection && vl.diskType == diskType && ttlEqual(vl.ttl, v.Ttl) {
+				// The reporter's own layout, or an rp-only difference:
+				// a replication change rolls through the nodes one at a
+				// time, so the same volume legitimately reports the old
+				// and new rp while it settles.
 				continue
 			}
 			var others []*DataNode