ROTJ:
When DS2 exploded, lots of construction workers, engineers, etc, died.
When Luke is dragging Vader towards a shuttle in the Death Star’s docking bay, there’s people scrambling in the background, yet no one stops to question why the Emperor’s menacing 2IC is being undressed by a blonde kid - everyone knew the station was doomed. I’m pretty sure the workers would have been the first to drop their tools and GTFO at the first sign of trouble.
The DS2 was finished, the incomplete look was part of the trap. Pretty sure all the contractors were packing up or gone by the time the Emperor arrived. Those were Imperial officers running around in a panic. No time to consider or gawk at Vader. To quote Douglas Adams, it was Somebody Else’s Problem or SEP. 😉
Or maybe Luke used the Force to conceal them both?