When he focused on Cassie again, Teddy wasn't sharing her eagerness but was just anxious. For a second, he almost just leaned back, too unsure to voice his concern, but he pushed on and asked, "If your dad is here, does that mean you're here, too? I mean, is there another me?"
Never mind another Kate and Eli-- if they tried looking for them, would they find this dimension's Kate and Eli? If they went looking for their parents, would meeting themselves cause some sort of glitch? Teddy wasn't sure if he could handle ripping a portal into a whole other dimension, two were more than enough to handle as it was.