There is slight problem with the speculative notion of PM having moved down a few steps in the brief interlude between Wiegman films last frame of entrance and Altgens photo capture.
The problem is that in Couch film sequence of the entrance which is AFTER Altgens photo, PM appears to be in the SAME position in the corner as he was in Weigman film.
As I understand it, Mr Mason, Wiegman starts filming over a second
after the Altgens photograph is taken. (I am following Mr Mark Tyler's calculations here.)
The figure with the (as I believe) coke bottle in hand need only step back/up one step to be in the PM position in Wiegman.
PM shows up in the Darnell film btw, not the Couch film.
So the chronology is: 1. Altgens 2. Wiegman 3. Darnell