My two are on different foods - Mishi is on Hill's prescription X/D and Mitzi is on non-prescription Science Diet Light/Hairball (because she's a heavy furball )

Their feeding stations are in different rooms and for the most part they don't eat each other's food, although Mitzi does sometimes sneak and eat Mishi's food; Mishi doesn't eat her food at all - he knows where HIS food is, although he's quite the gentleman when it comes to sharing. The food is left out for them to free-feed. I guess I'm just lucky.