Merge pull request #9524 from m-kuhn/offline_editing_duplicate_layer_names_backport_3_6

[offline editing] Support for layers with identical names

Author: m-kuhn

src/core/qgsofflineediting.cpp

@@ -642,7 +642,7 @@ QgsVectorLayer *QgsOfflineEditing::copyVectorLayer( QgsVectorLayer *layer, sqlit
       char **options = nullptr;
 
       options = CSLSetNameValue( options, "OVERWRITE", "YES" );
-      options = CSLSetNameValue( options, "IDENTIFIER", tr( "%1 (offline)" ).arg( layer->name() ).toUtf8().constData() );
+      options = CSLSetNameValue( options, "IDENTIFIER", tr( "%1 (offline)" ).arg( layer->id() ).toUtf8().constData() );
       options = CSLSetNameValue( options, "DESCRIPTION", layer->dataComment().toUtf8().constData() );
 
       //the FID-name should not exist in the original data