I was onto trimming the forearms and biceps and each of the corresponding pieces are identical, fit perfectly inside each other, with landmarks and markings all on the same side (ie they don't mirror each other), difficult to see in some of the photos but easiest to pick up on the inside biceps with tapering both on the right side and thumb prints on the left.
When I look at the leg pieces there are clearly opposing pieces for upper and lower legs, but not for the arms, just wanted to check before I start trimming that I haven't got 2 left arms.