Well, it wouldn't really be the same. Even if she were conditioned and behaved just like Padme it would always be "someone else" as it were. Hope that makes sense :/
Of course, a deranged/obsessed person or a more materialistic person might go ahead and do it just for a facsimile, but that would seem outside Vader/Anakin's character I think.
My question though, is why Palpatine didn't clone Vader and replace him... he's a shifty, evil enough dude, and theoretically a clone would've had all of Vader's skill in the force, a healthy body (instead of a completely amputated one in a breathing suit) plus Palpatine could've conditioned him from scratch- nixing any chances of what happened in ROTJ.
That would suck of course, but seems like something Palpatine would do- as one book put it he pretty much saw everyone and everything as a means to an end.
Perhaps he thought having the
Anakin, and the statement of his descent into the darkside and the extent of his rage, was worthwhile enough. After all, the dark side is all about rage and hatred- as you see in the way Palpatine goads Luke on in ROTJ.
One theory would also say that Palpatine didn't have access to cloning technology outright since the clone army came from Kamino, but surely he could've siezed the place and stolen it, I think. The Expanded Universe, though many movie fans disregard it, states (according to the Thrawn Trilogy at least) that Palpatine had some stolen cloning cylinders stockpiled in a secret warehouse with other interesting junk, but wasn't clear how much he used them. I believe the Dark Empire comics plot revolves around Palpatine cloning himself and transferring his soul to new bodies, though.
And another technical quandry is bought up by the Thrawn trilogy that, oddly enough, might explain why Vader was never cloned; it says many early attempts at clones didn't think or function properly unless they were grown very slowly (and, incidentally, the army of the republic was growing for at least 10 years IIRC). Thrawn found a way around it by using Ysalamiri, which repel the force, to keep the force from affecting the clones- the problem was that two identical entitites caused problems with the force and thus drove the clone mad. But obviously that wouldn't be so good for cloning a Sith Lord- then they probably couldn't use the force at all!
One further bit of coincidental technical information I can garner from the Thrawn trilogy on this subject is the existance of Joruus C'Baoth, a mad clone of a Jedi killed a few years before the Clone Wars. I'm not sure but I kind of got the impression Palpatine was the one who cloned him- that would make sense if he was an experiment to see if he could use the same method on Vader, eh?
Anyway, sorry for the lengthy speech, hope it helps you think some.