two kinds of scopes?


This my be a stupid question or maybe its been asked before. I started building my Boba Fett blaster and ive been looking at all kinds of reference pics. Ive noticed that on some pics of the ROTJ blaster he has a long scope with 2 mounts and in other pics he has a much shorter scope with only 1 mount. What gives? At first i thought that part of the scope might have been accidentally croped out of the pic but ive seen quite a few pics like this with the shorter scope. Anyone know why? :confused