[OVERSIGHT] 2 disc games aren't really possible as far as i can see?

tl;dr some gamecube games came on 2 discs and since each disc is valid(and runs, for example on RE4 you can start where you left off if you got to the point where you needed disc 2)
and since these two discs (assumedly) share similar code, I want to build both discs from the same source code.
thanks :3

It's totally possible to support 2 disc games, but you will currently have to set them up as two different "versions".