Jeff, put down the wrenches and step away!
Seriously though, what the hell? Must be some kind of issue with a register so the computer/motor knows where the light is. I hate to say it since I don't know how big a job it is, but you may need to take both out and see what's different between the right and left side.
And Marck, I think it's a late c5 but not sure of the year.