[Alright. He can't say he can't see that happening, in a different sort of timey wimey-memory loss sort of way - but still, how or why would he have a twin that looked so much like him, down to the eye-thing? He finds he has to be insistent that much is not possible, shaking his head.]

Pretty sure I don't have a twin. So I don't know if you're crazy or not, or if it's this place [there's an emphasis on 'this place' making it sound he believes it's that, more than Peter being necessarily crazy], but I still don't know who you are...

[This is where a name would have come in handy, but given that he doesn't know it, he breaks off for a second.]

Uh, who are you even?