I'm not sure if you're serious or if you're just trolling. Either way I think it would be kinda cool to see Vader and Sidious fight with lightsabers for a final battle in ROTJ, just not the way you presented it. Maybe it could be like... Vader beats Luke in their fight together and with Luke on the ground in defeat the Emperor tells Vader to finish him off. This is when Vader can't kill his son and has flash backs to Padme. With that Anakin has returned and he turns on the Emperor. The two battle it out, red lightsaber against red lightsaber, in the Throne Room. After a good, and almost even fight, Sidious cuts off Anakins hand. With Anakin kneeling in defeat the Emperor lashes out a burst of Force Lightning. While still being shocked Anakin rushes forward, grabs the Emperor, and throws him down the shaft to his death. Then the rest of RotJ plays out the way it normally does. I actually like the way RotJ is, I just did that for fun.