Matroska with multiple video tracks plays all simultaneously
If a Matroska file contains multiple video tracks, VLC will play them all simultaneously, creating a separate window for each track beyond the first.
When this happens, using the Video Track menu option does not work to change the video track, except that you can choose “Video Track→Disabled” and then choose a single track.
Obviously, it should only play the default track by default, and the Video Track menu should work.