For the Major Advancement: Make a Second Character, how does this work? Do they have two characters that they rotate in and out at will? If so, how do they earn XP and cred?
Otherwise, do they now have two characters in play at the same time? Or is this more of an MC’s personal interpretation?
Totally up to the GM and players. Usually I’ve seen groups retire previous PCs to become NPCs. If you as GM and the players are cool with doubling up on characters you can say that one PC is off doing other jobs. They can earn XP if you choose to let them