Backport pull request #15858 from jellyfin/release-10.11.z

Fix playlist item de-duplication

Original-merge: 78e3702cb064fc664ed1a658ad534cf66f5373d3

Merged-by: crobibero <cody@robibe.ro>

Backported-by: Bond_009 <bond.009@outlook.com>

MediaBrowser.Providers/Playlists/PlaylistMetadataService.cs

@@ -72,7 +72,7 @@ public class PlaylistMetadataService : MetadataService<Playlist, ItemLookupInfo>
             }
             else
             {
-                targetItem.LinkedChildren = sourceItem.LinkedChildren.Concat(targetItem.LinkedChildren).Distinct().ToArray();
+                targetItem.LinkedChildren = sourceItem.LinkedChildren.Concat(targetItem.LinkedChildren).DistinctBy(i => i.Path).ToArray();
             }
 
             if (replaceData || targetItem.Shares.Count == 0)