[To say that Wally was a tad bit skeptical about the whole "alternate universe" explanation would be an understatement, but he becomes more of a believer after he gets a good look at the guy who suddenly screeched to a halt in front of him. He may be younger and shorter than the Barry Wally knows, but there's no way the uncanny resemblance to his uncle is a coincidence. He even has the super-speed.
He blinks a few times with his mouth hanging open in shock before:] You...really weren't kidding, were you?