Against better judgment I'm going to have one final go at trying to explain why the clone theory was even remotely considered, because it seems that most people who dismiss it out of hand misunderstand that those who have considered it a
possibility (that they will leave open)
are not advocating for it! It's just been considered as a potential plot device to explain some imagery that seems to go beyond Superman just being the stern new sheriff in town.
Personally, I don't think that the clone device is needed at all and there are plenty of other ways in which Batman might be pitted against one another by Lex in addition to their different ideologies about their respective roles as society's protector. (I have
my own theory about it that is clone-free.) But that said, the clone device would all depend on execution, and is not necessarily something that would automatically ruin the film. Months ago Kryps, Clark and I all concurred that we're
not hoping for it--just that if it is used, that it is done well! My hope is that in the scene of Superman kneeling before Lex (and although not as clear, perhaps a couple of similar looking ones with him wearing the spit curl) that there's a satisfying explanation for why Superman is wearing such a hateful, sneering expression. (To my eye that is more than just stern or grimly determined.) That's all! Hopefully we'll get that without Superman being a clone. I mean the venom in his look could just be directed toward Lex for whatever leverage Lex has exerted over him there.
The "Bizarro" speculations are I think by now more clearly framed within Lex performing cloning experiments with Zod--either using his stem cells to grow a fetus in the birthing chamber, or by reanimating Zod's corpse... but in either case evidently splicing in Bertron's DNA code for Doomsday. In the comics it is Lex's efforts to clone from Zod that result in Bizarro. So the term "Bizarro" would have a rather loose connection in this film. Here I would not expect the traditional Bizarro (a figure that is politically incorrect due to his cognitive deficits) but rather a creation that plays up the Frankenstein monster parallels that Bizarro has always had.
Anyway, I've seen a tendency to be both dismissive and derisive toward attempts to theorize about what results from Lex's cloning experiments in this film! But neither of those two things are really all that whacked out. They are actually both fairly thoughtful concepts...
As I said, though, I
do expect that we will see Doomsday to have been the result of cloning experiments by Lex in some way using Zod's corpse. However Clark, Krypton, and I all agreed back when that once it was clear that Doomsday was in this film, for that reason we actually do
not expect to see a clone of Superman created as a device to pit Supes and Bats against one another. It would feel redundant to have two cloned monsters.
I'm now more than ever looking forward to discovering the explanation for what appears to be a sort of sneering, venomous Superman that I would still maintain we have gotten glimpses of (and gets condensed in Batman's dream). I do believe that there are images of Superman that suggest that something unusual is going on with him--we'll just have to find out what it is! And honestly, believe me, I do hope that it is not a clone.
t:
really fits well with the clone theory 
Of course there could be "real" Superman scenes throughout all these clips, and cloned Superman as well. If it is even a part of the story.
