[dragonwriter]

> even copyrighting them

copyrighting isn't (at least, in US law) a distinct action people take. If it is subject to copyright, the it is copyrighted on creation by operation of law.

> when X already exists in the real world

To the extent that a thing is copyrightable by nature , coincidental existence of an identical thing doesn't make it any less so. It might make it difficult to prove it as a creation rather than a copy if challenged (or to prove that an alleged infringement was a copy of it rather than the identical doppelganger), though.