I don't think that's an easy question for most people to answer when they really think about it.
We're used to have our mind as an inviolable private resource, not something that can be copy-pasted, edited and experimented freely with. Your last instance went insane in an interesting way? Let's keep it and run another. Make them interact for extra amusement.
And can we at least look at other comments before responding? I'm not going to reply to 30 copies. I know there's collisions but this argument is one I think you can assume most people are aware of. Snape kills Dumbledoor kinda thing. Book and movies have been out for so long it's not a spoiler.
In the case of a copy or upload, there is a clear disjoint process. Both entities can exist at the same time. For both of them to be "you", "you" have to be simultaneously experiencing both experiences (that doesn't sound very fun...)
As for the sleep/unconscious/etc stuff. I think people should read into this more before bringing them up. There's a lot more going on than a discrete "on" and "off" state. Brain activity does not cease. There are definitely cases where brain activity ,,appears,, to cease, but that is a distinctly different phenomena and is the result of precision of measuring devices. This stuff fits more under the Ship of Theseus argument though.