Brightness and Contrast Issue on Calibration

I've started having migraine issues the last few years. On one machine I have, I wanted to create a few different monitor calibration sets, so that I could switch between sets that were for accurate work, and then sets that were lower in brightness and color temp, which would be easier on my head. I'm using 10.5.8 and an external ViewSonic. I just now realized, that the contrast and brightness settings seem to be overridden by the monitor. In other words... Say that you go to calibrate... You start off by manually setting the contrast and brightness, then adjust all the other settings and save the calibration. If you are using that calibration set and manually change the brightness and/or contrast... clicking on any calibration set, will NOT return the brightness and contrast to the settings you had them at, for that saved calibration set. ie: There's basically only one brightness and contrast setting you can have, at any given time, no matter what calibration set you’re running.

This doesn't seem right. Has it always been like this?