I scanned some photos from the new Making of The Empire Strikes Back book that I found interesting. I did not watermark these as they are not my photos and are publicly available.
Luke and Vader practicing the duel. Mark using the ANH shared Luke/Vader stunt, Prowse using the ANH V2 saber. You can tell Marks using the ANH stunt because you can see the white on/off button on between the grips, the old style Graflex knob on top and the Graflex glass eye on the bottom.
Different day, Mark is now using the V2 and Bob the shared ANH stunt (again, the white on/off visible )