I've finished the game once now, and I intend to do it 2 more times, but the question is this: Will it create a new Final-Save each time? I assume this is a special save to be used with the expansion since it resurects all of your characters and places you at the point just as you start hell..so what's the deal?
It's a good idea to rename the finalsave folder so that you remember wich game it's from. Your character however should have been exported into a personal file wich can be imported in the eventual sequel.