Even with the T-Rex defeated, the T-Rex music gets wrongfully retriggered and plays a second time when you walk back out of the valley, on your way to finish the level.
I can't reproduce this. Have you loaded a savegame between the first play and the second one? If not, could you give instruction how to trigger this bug?
Even with the T-Rex defeated, the T-Rex music gets wrongfully retriggered and plays a second time when you walk back out of the valley, on your way to finish the level.