I recall seeing shots of Temeura in a spandex suit of some kind wearing what looked like an old Stormtrooper helmet, so he had a physical prop to use.
CGI clones for the battle scenes makes sense, but the logic of not even having a single costume to wear on the set for a simple scene between two actors escapes me. Then again, they stuck a CGI Artoo into shots that could have been easily done with the real prop in ROTS. Sticks out like a sore thumb.