Wherever discrete tracks were available, they were used to make the Rock Band Beatles game. So for what they had for Sgt. Pepper, for example, they used that. Remember that was just a pair of four track machines and a shitload of bounce-downs, so there's some stuff that wasn't separated.

For those where separate tracks weren't available, as I said above, they did some arcane stuff to simulate the same effect that discrete tracks would have given you.

Those resulting separated and faux-separated tracks are extractable from the game data, just sayin'.