Such specific, rational questions! It's kind of charming.
Sometimes they're the same person from the same universe, and sometimes they aren't.
The mechanics of that get a little technical. Basically it depends on how complicated the retrieval would be. Even Acumen draws the line when it approaches an estimated retrieval time of three hundred years. Then it becomes more pragmatic to just hold a new trial for a different but nearly-identical timeline of the criminal in question, and deprecate the old code entirely.
But every version of every criminal who's ever been here is still here. Unless they died. [some scattered, muffled giggling]
Yes, of course. After they die, they've served their time. It wouldn't be fair to hang onto that code.