Have you been able to findI am almost positive there is 2 different stunts in the throne room.. the v3 and a extra stunt
1) ANY stunts in the throne room with a black ring under the emitter lip (meaning this chrome tape over the black was a quick mock up for filming the duel)
2) ANY stunts with a black emitter in the throne room?
this would really nail it home that this emitter is a replacement. (maybe even done for the walk-through with Vader holding it or later)