[Playlist Loader] Deduplicate loaded items

Deduplicate loaded tracks, to prevent duplicate items when adding a
folder that happens to contain playlists or CUE sheets referencing the
very same files.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Playlist/PlaylistLoader.m

@@ -455,6 +455,9 @@ static inline void dispatch_sync_reentrant(dispatch_queue_t queue, dispatch_bloc
 		[self setProgressStatus:60.0];
 	}
 
+	// Deduplication of contained URLs
+	[fileURLs removeObjectsInArray:containedURLs];
+
 	DLog(@"File urls: %@", fileURLs);
 
 	DLog(@"Contained urls: %@", containedURLs);