SW: Unusual boss music issues in level 20

In level 20, you refight both the Sumo and Serpent God bosses before dealing with the final boss, Zilla. Normally, the game starts the boss music when the player first enters the boss arena, then stops once the boss' death animation is complete. However, I've noticed two unusual cases regarding it.

Case 1: The boss music did not stop once the Sumo was defeated. Saving a game after this, then loading it, would play the music at a lower volume, but it was still there. The music would restart at regular volume once entering the Serpent God and Zilla's chambers, but would continue to play after their deaths. This happened twice.

Case 2: The boss music stopped once the Sumo was defeated, but did not start again once the Serpent God nor Zilla were encountered. This happened once.

There dosen't seem to be any way to reliably repeat these issues. I had two testing runs through level 20 where the "boss music never stops" issue did not happen, then it popped up again in the third one. Interlopate SO doesn't seem to have an effect on this, as Case 1 happened with it on and off.

Version used is VoidSW r9028-02eff8c8.