I'm not sure why Chris wouldn't leave this stuff in my hands...
Chris has informed you correctly. He is correct when referring to the actual figure variations, but not the carded variations.
Here are all the known carded variations:
Scout Trooper (clean)
Scout Trooper (dirty)
I know this just adds 1 other variation, but when you are collecting to complete a carded set, the variations (serial #'s) count. If you are collecting loose and just the figure variations, then Chris is correct. That's my 2 cents.