If you made a copy of you down to the atomic level, and this copy appeared on a planet several kilometers away, is that new copy "you"?
Does that new copy become "you" if you simply incinerate the original?
Does that new copy become "you" if you simply incinerate the original?
If we clone A, then from A's perspective we now have A-Prime. A-Prime is unaware and believes they are A, who now presumably has been killed. If anyone didn't observe this happen, then A-Prime essentially -is- A. If they did observe it, then they know that it's technically A-Prime.
So I guess the difference is being able to observe the gradual changes. It's more tricky when discussing an inanimate object like a ship that doesn't care either way.
Btw, we talk about replica's but that's only because we assume the process leaves an original and a copy, but that's not necessarily so, for example a photon of high energy can split into 2 photons of lower energy. We are not talking about originals and replica's there. One can imagine that our duplication process follows similar rules.
When copying or simply making 2 out of 1, for computers, both still have computer-0 in /etc/hostname so there's that... It's just that neither of the computers will complain when we change their designation at random.
This leaves me feeling weird about the destruction of an original in any copying process. The destruction during copying feels ok, but doing it afterwards feels very bad. It's like we want consciousness to be continuous in time. But why? Again, Permutation City goes into this in a nice way...