Seems like my misunderstanding is by coming across moments in youtube vids (and even on my own disc?) where it does play the disc 1 music again, at random, for reasons I don't understand. The first time I got a battle on Disc 2 it played the Disc 1 music, then stopped, hence why I wondered if it was an issue. I wonder if it's a bug in the game itself or something. This is my first time through. Thanks again for the great work.
The only disc 1 results music that plays on disc 2 is the perfect win music. Which that happens when you win the battle without taking any damage.