I have an idea for a Sidious/Palpatine in TPM-ROTS.

Darth Sidious in PT is just a Palpatine in Sith robes and everybody at once figured out that they are the same character and this plot twist in Ep.III is not as surprising as it should be.

My first idea is: add Palpy's disfigured face from ROTJ to the Sidious- his real appearance will be just a some kind of a force mask. Surprise saved, if Star Wars watched in order Ep.I-Ep.VI

2nd idea: Palpatine looked more older in AOTC than in ROTS. Somebody could make Palpy's face for ROTS that would look like something between AOTC and ROTJ. This would support the original concept of the Emperor's face disfigured by using Dark Side for a very long time.

In both ideas: force lightning in Windu-Sidious duel will not have any influence sent back to Palpatine.