Backup your game.db in a safe location, and start a new game. As long as you keep some discipline in naming the files, there ought to be no problem switching between any number of SP save-games.
Or see this topic:
Backup your game.db in a safe location, and start a new game. As long as you keep some discipline in naming the files, there ought to be no problem switching between any number of SP save-games.
Or see this topic: