Is Sarang a complete idiot?

[Kein]

Or did he just not take Computer Science classes as a kid? Or anything remotely based on real science for that matter? If he did, he'd know that cut-and-paste and copy-and-paste both copy the original.

He and his followers should've changed their motto to "We put our faith in the reality of cut-n-pastey!", seeing as they tried doing that IRL.

I guess you've skipped all the notes in the game and just went through it? Sarang explicitly mentioned that a copy will be identical or very close to the original right after the process and/or short after. But with time the difference in experience will alter the development of their conspicuousness, of their self, thus there won't be any more two similar copies.

I mean, as long as his copy knows 'my other self killed himself at theta nd I'm actually a copy, not him, he's dead' and he has no illusions then I guess he's an okay guy.

That's kinda the idea, i think. Well, may be he is not that clear on this as Cath but his strong position guarantees him he will never let anyone make a another copy after he is in Ark. Or, at least, a copy without "original" (it was made from) destruction.