We Has a Theory!

In the season finale of Fringe, Walter was at the grave of a Peter Bishop, who died at age seven. We also know that Walter often brings up memories of a sick, dying Peter that Peter himself does not remember.
When we first saw the grave, we thought that maybe Peter was a clone. But if he was cloned after the real Peter died, in 1985, Peter would only be twenty-three. Obviously, he is older.
Someone brought up that Olivia and William Bell were meeting in the Twin Towers, in the alternate reality, so we had a thought (that was basically confirmed by everyone in the Fringe fandom)…
Walter took Peter from the alternate reality.
Now, Mila has another theory. She says that the Observer saved Peter and Walter from the car crash. Well…what if the real Peter actually died then, but the Observer brought the other Peter and left him there instead. Eh?
Bryn