That's a good theory, but what about this quote from the Flash News Page, it clearly says that Caitlin will be the one surprised, so even when Barry approaches, she would kiss him.

"Caitlin isn't holding out for Barry but she wouldn't turn him away"

well i'm still hoping that it's caitlin who is the meta human, even though it doesn't really seem like it now. i keep thinking that time travel will come into play for this and both of them won't even remember it if it's actually fake barry. even though one of them isn't real, one of them did kiss back and id just hate if that fallout was erased lol

Oh man, they should! After all Caitlin will be going through knowing the real identity of Wells.

"Barry's" elbow is moving during the kiss. He really whipped her around

But why would Barry kiss Faitlin (Fake Caitlin) to prove she is fake? why not just ask her something personal ? like what song did they sing at karaoke night ? or what disease did she tell Eddi and Iris he has ? or what is firestorm?why kiss her? I'm sticking to the metahuman being Barry, based on the sheer confidence of that spin and kiss. Barry is far too much a fumbling adorable dork (and he tends to vibrate in those scenarios) to be that suave. And also I like that Caitlin reciprocates back the kiss thus confirming what we all suspected, she's been trying to move on...to Barry .But I like the outside the box thinking about the theory.