diff --git a/service/matching/matching_engine.go b/service/matching/matching_engine.go
index df83f570984..4ba0b62666f 100644
--- a/service/matching/matching_engine.go
+++ b/service/matching/matching_engine.go
@@ -849,8 +849,6 @@ func (e *matchingEngineImpl) UpdateWorkerBuildIdCompatibility(
 		updateOptions.TaskQueueLimitPerBuildId = e.config.TaskQueueLimitPerBuildId()
 	case *matchingservice.UpdateWorkerBuildIdCompatibilityRequest_RemoveBuildIds_:
 		updateOptions.KnownVersion = req.GetRemoveBuildIds().GetKnownUserDataVersion()
-	default:
-		return nil, serviceerror.NewInvalidArgument(fmt.Sprintf("invalid operation: %v", req.GetOperation()))
 	}
 
 	err = tqMgr.UpdateUserData(ctx, updateOptions, func(data *persistencespb.TaskQueueUserData) (*persistencespb.TaskQueueUserData, bool, error) {
diff --git a/service/matching/version_sets.go b/service/matching/version_sets.go
index 913ebffd87d..5d3a1df46a8 100644
--- a/service/matching/version_sets.go
+++ b/service/matching/version_sets.go
@@ -153,21 +153,17 @@ func hashBuildId(buildID string) string {
 }
 
 func shallowCloneVersioningData(data *persistencespb.VersioningData) *persistencespb.VersioningData {
-	clone := persistencespb.VersioningData{
-		VersionSets: make([]*persistencespb.CompatibleVersionSet, len(data.GetVersionSets())),
+	return &persistencespb.VersioningData{
+		VersionSets: slices.Clone(data.GetVersionSets()),
 	}
-	copy(clone.VersionSets, data.GetVersionSets())
-	return &clone
 }
 
 func shallowCloneVersionSet(set *persistencespb.CompatibleVersionSet) *persistencespb.CompatibleVersionSet {
-	clone := &persistencespb.CompatibleVersionSet{
-		SetIds:                 set.SetIds,
-		BuildIds:               make([]*persistencespb.BuildId, len(set.BuildIds)),
+	return &persistencespb.CompatibleVersionSet{
+		SetIds:                 slices.Clone(set.SetIds),
+		BuildIds:               slices.Clone(set.BuildIds),
 		BecameDefaultTimestamp: set.BecameDefaultTimestamp,
 	}
-	copy(clone.BuildIds, set.BuildIds)
-	return clone
 }
 
 // UpdateVersionSets updates version sets given existing versioning data and an update request. The request is expected
@@ -487,9 +483,21 @@ func ClearTombstones(versioningData *persistencespb.VersioningData) *persistence
 }
 
 func PersistUnknownBuildId(clock hlc.Clock, data *persistencespb.VersioningData, buildId string) *persistencespb.VersioningData {
+	guessedSetId := hashBuildId(buildId)
+
 	if foundSetId, _ := worker_versioning.FindBuildId(data, buildId); foundSetId >= 0 {
-		// it's already there
-		return data
+		// it's already there. make sure its set id is present.
+		set := data.VersionSets[foundSetId]
+		if slices.Contains(set.SetIds, guessedSetId) {
+			return data
+		}
+
+		// if not, add the guessed set id
+		newSet := shallowCloneVersionSet(set)
+		newSet.SetIds = append(newSet.SetIds, guessedSetId)
+		newData := shallowCloneVersioningData(data)
+		newData.VersionSets[foundSetId] = newSet
+		return newData
 	}
 
 	// insert unknown build id with zero time so that if merged with any other set, the other
@@ -498,7 +506,7 @@ func PersistUnknownBuildId(clock hlc.Clock, data *persistencespb.VersioningData,
 
 	newData := shallowCloneVersioningData(data)
 	newData.VersionSets = slices.Insert(newData.VersionSets, 0, &persistencespb.CompatibleVersionSet{
-		SetIds: []string{hashBuildId(buildId)},
+		SetIds: []string{guessedSetId},
 		BuildIds: []*persistencespb.BuildId{{
 			Id:                     buildId,
 			State:                  persistencespb.STATE_ACTIVE,
diff --git a/service/matching/version_sets_test.go b/service/matching/version_sets_test.go
index d3fb07a6622..876c3542551 100644
--- a/service/matching/version_sets_test.go
+++ b/service/matching/version_sets_test.go
@@ -863,3 +863,34 @@ func TestPersistUnknownBuildId(t *testing.T) {
 	assert.Equal(t, 1, len(newSet.BuildIds))
 	assert.Equal(t, "new-build-id", newSet.BuildIds[0].Id)
 }
+
+func TestPersistUnknownBuildIdAlreadyThere(t *testing.T) {
+	t.Parallel()
+	clock := hlc.Next(hlc.Zero(1), commonclock.NewRealTimeSource())
+
+	initial := &persistencespb.VersioningData{
+		VersionSets: []*persistencespb.CompatibleVersionSet{
+			{
+				SetIds:                 []string{hashBuildId("1")},
+				BuildIds:               []*persistencespb.BuildId{mkBuildId("1", clock), mkBuildId("2", clock)},
+				BecameDefaultTimestamp: &clock,
+			},
+		},
+	}
+
+	actual := PersistUnknownBuildId(clock, initial, "1")
+	assert.Equal(t, initial, actual)
+
+	// build id is already there but adds set id
+	actual = PersistUnknownBuildId(clock, initial, "2")
+	expected := &persistencespb.VersioningData{
+		VersionSets: []*persistencespb.CompatibleVersionSet{
+			{
+				SetIds:                 []string{hashBuildId("1"), hashBuildId("2")},
+				BuildIds:               []*persistencespb.BuildId{mkBuildId("1", clock), mkBuildId("2", clock)},
+				BecameDefaultTimestamp: &clock,
+			},
+		},
+	}
+	assert.Equal(t, expected, actual)
+}