They obviously took a second "salute" pic, after a short spot of walking around (the pictures were taken at different times). And maybe he left his camera somewhere, perhaps it was hard to plant the flag/place instruments with a bulky camera on his chest.
More likely:
There were two camera's, one for black and white photo's the other for colour.
This would mean potentially a reposition and change of camera during the "salute" photo and a change of camera where one is removed from his chest an used in the other shot.