That's how it worked in Lion, but Mountain Lion behaves differently -- you get the duplicate with its file name selected, so you can rename it, but the original

That's how it worked in Lion, but Mountain Lion behaves differently -- you get the duplicate with its file name selected, so you can rename it, but the original stays modified unless you think to immediately pick "Revert to last saved version". I actually liked the Lion behavior better. (Now I wish I'd had the chance to try out the Mountain Lion beta before release, so I could have filed a bug for this.) That's what we get for everyone complaining about the lack of "Save As"...