I'm pretty sure the shot of Luke and Vader is legit. Luke's pose only seems odd as the photo catches him in mid-stride.
Some publicity shots could have been a little disinformation campaign on the part of Lucasfilm just like the phony script pages were.
I remember one old fan club newsletter intwerview where one of the people working on the film casually mentioned Aunt Beru was still alive!
Interesting that one of the rebel troops is holding Luke's lightsaber though!