Yayo, the dream starts out with Peter lying on the ground and getting up and walking through all the cars. You see DL, Nicki, Matt Parkman, Hiro, Simone, Issac, Claire, Nathan, and even the invisible man but you never see the radioactive man (sorry, I forget his name). So, either Peter has learned how to keep a power after he has taken it or they are intentionally not showing radioactive man.
Linderbee, I thought about that at first as well but in the last episode Nathan specifically speaks to him as Peter. He tells him that he's not going anywhere. Also, if it's not Peter why would Simone run to him? The only answer I can come up with is that he's retaining the power somehow but that would seem to make him entirely too powerful for a show that supposed to show the balance of good and evil.