same problem here. Didn't found anything on web about that, so decided to write here.
I've got different exposures for RT and normal render as well.
Both are camera selected, no perspective view.
Got this problem for two or three scenes. Don't know how to proceed.
Sometimes works very well, and then crash. Stop working, and the illumination from RT that it's correct, on normal render is overexposed.
Anyone who have discover something?
Thanks in adv.