Hiding memories

Is it possible in a system to "overlap" a really bad memory with another bad, but not horrible one to hide it?

I'll hopefully be able to explain specifics a bit later. I'm way too scrambled right now.

The mind is capable of a lot, especially when it comes to protecting itself. Alts can hide, memories can be masked, even two good memories can overlap just by accident.

One of us has memories of a full life that in no way resembles what this body has actually experienced. He apparently has no memory gaps at all, even though his memories are obviously false- parents that are not ours, an address that does not exist, experiences on dates where I know for a fact something else entirely was going on. It's really weird. I really do wonder sometimes though if his memories are the real deal.