I was thinking the exact same thing, the original(s) may be two separate images. The shadows on the faces do seem to match, but he could have fixed that. There's something about the positioning of the people that seems to hint at them having been spliced together, but I can't say for sure.
I was keeping an eye out for that as I was Googling, looking not just for two people posed that way, but for each individual. I can't search any more this morning, plus I'm just on dial-up and it's slow loading even the thumbnails!
I won't be able to search much longer. I have a couple of books downstairs that may have some photos. I also think I am going to check the National Archives photo collection.