bcp wrote
... It seems unlikely to me the photographer would move several yards between photos....
As unlikely as it seems, I think that's what happened. When you look at the full image from both photos, you'll see that they are the same dimensions & proportions, just with one in portrait and the other landscape, and that the rock and depot are both practically the same size. This seems to indicate that the distance from the camera to the depot or rock didn't change much and the camera had the same plate size and lens focal length (or the focal length and plate size changed in exact proportion, which isn't likely). It's unlikely that two photographers brought identical cameras or that Jackson lugged two nearly identical cameras up the hill (although he must have at least brought two plates). Everything else is just too close for these to be from different trips to the site. I'm pretty sure that my print for the portrait-oriented photo is a contact print from the original glass plate, and it's 11"x14". This is much smaller than his 18"x22" mammoth plates, but I understand that he used a variety of cameras.
The two photos are lined up in the following image so that dome rock lines up. The landscape-oriented one has the depot lower and to the right with the background ridge higher. If I have figured out the perspective correctly, this puts the camera to the left and above the location for the portrait-oriented shot.