diff --git a/pkg/service/datastore/datastore.go b/pkg/service/datastore/datastore.go
index 8f8376d..0bd9774 100644
--- a/pkg/service/datastore/datastore.go
+++ b/pkg/service/datastore/datastore.go
@@ -1330,6 +1330,25 @@ func (ds *DataStore) SaveConfiguredSources(account, device string, sources []mod
 		} `xml:"sourceKey"`
 	}
 
+	// Deduplicate by ID before saving; first occurrence wins to preserve established data
+	seen := make(map[string]bool)
+
+	deduped := make([]models.ConfiguredSource, 0, len(sources))
+	for i := range sources {
+		s := &sources[i]
+		if s.ID != "" {
+			if seen[s.ID] {
+				continue
+			}
+
+			seen[s.ID] = true
+		}
+
+		deduped = append(deduped, *s)
+	}
+
+	sources = deduped
+
 	// Ensure SourceKey is populated from legacy fields if necessary before saving
 	// and map to persistentSource to avoid custom MarshalXML for disk storage
 	persistSources := make([]persistentSource, len(sources))
@@ -1591,6 +1610,14 @@ func (ds *DataStore) GetETagForPresets(account, device string) int64 {
 	return info.ModTime().UnixNano() / int64(time.Millisecond)
 }
 
+// HasConfiguredSources reports whether a Sources.xml file exists for the given account and device.
+func (ds *DataStore) HasConfiguredSources(account, device string) bool {
+	path := filepath.Join(ds.AccountDeviceDir(account, device), constants.SourcesFile)
+	_, err := os.Stat(path)
+
+	return err == nil
+}
+
 // GetETagForSources returns the ETag (modification time) for the sources file for a specific device.
 func (ds *DataStore) GetETagForSources(account, device string) int64 {
 	path := filepath.Join(ds.AccountDeviceDir(account, device), constants.SourcesFile)
diff --git a/pkg/service/handlers/server.go b/pkg/service/handlers/server.go
index 5fcf6a7..d7328c7 100644
--- a/pkg/service/handlers/server.go
+++ b/pkg/service/handlers/server.go
@@ -569,12 +569,14 @@ func (s *Server) handleDiscoveredDevice(d models.DiscoveredDevice) {
 		return
 	}
 
-	// 8. Ensure default sources exist if missing
-	if sources, err := s.ds.GetConfiguredSources(accountID, deviceID); err == nil {
-		log.Printf("Creating default Sources.xml for device %s", deviceID)
+	// 8. Create default Sources.xml only when no sources file exists yet
+	if !s.ds.HasConfiguredSources(accountID, deviceID) {
+		if sources, err := s.ds.GetConfiguredSources(accountID, deviceID); err == nil {
+			log.Printf("Creating default Sources.xml for device %s", deviceID)
 
-		if err := s.ds.SaveConfiguredSources(accountID, deviceID, sources); err != nil {
-			log.Printf("Failed to save default sources for %s: %v", deviceID, err)
+			if err := s.ds.SaveConfiguredSources(accountID, deviceID, sources); err != nil {
+				log.Printf("Failed to save default sources for %s: %v", deviceID, err)
+			}
 		}
 	}
 
@@ -620,12 +622,14 @@ func (s *Server) handleDiscoveredDeviceFallback(d models.DiscoveredDevice) {
 		return
 	}
 
-	// Ensure default sources exist if missing
-	if sources, err := s.ds.GetConfiguredSources(accountID, deviceID); err == nil {
-		log.Printf("Creating default Sources.xml for device %s (fallback)", deviceID)
+	// Create default Sources.xml only when no sources file exists yet
+	if !s.ds.HasConfiguredSources(accountID, deviceID) {
+		if sources, err := s.ds.GetConfiguredSources(accountID, deviceID); err == nil {
+			log.Printf("Creating default Sources.xml for device %s (fallback)", deviceID)
 
-		if err := s.ds.SaveConfiguredSources(accountID, deviceID, sources); err != nil {
-			log.Printf("Failed to save default sources for %s: %v", deviceID, err)
+			if err := s.ds.SaveConfiguredSources(accountID, deviceID, sources); err != nil {
+				log.Printf("Failed to save default sources for %s: %v", deviceID, err)
+			}
 		}
 	}