Darth Venal said:
The green mockup definitely looks less like R2D2, but you're wrong about it not being R2 in the original shot. It is. And I'm sorry, but no matter how many times anyone tries to tweak that shot, the fact that it's Ben, Luke, C-3PO and R2-D2 is inescapable. It is clearly framed that way, unless you're trying to say that Gilbert Taylor framed three of them and some other random droid that just happens to look exactly like R2-D2?

And the alternate shot is not in the movie. There are simply two R2-D2s on set to shoot the turn.

I never said that it wasn't supposed to be R2. All i said was that the droid used wasn't the same droid used for R2 in the rest of the movie because it has grey panels and that changing the colour worked because of this. It was done because R2 went off screen to the left as the camera pans then is suddenly in front of them which would have been impossible and it was so obvious that it was 2 separate robots used.