I just bought two new monitors that ended up having vastly different color temperature. These are some of the cheap 27" 1440p monitors from Korea, so they have no OSD for calibration and exchanging them would be difficult and likely quite expensive. I'd like to apply different color profiles to them so that they appear similar, but since I have them set up in TwinView I'm unable to use any of the standard calibration tools. I'm able to calibrate the colors individually in the nvidia-settings gui, but the settings don't appear to be saved anywhere (when I reboot or open nvidia-settings, they're reverted to stock). I've tried saving the settings to .nvidia-settings-rc and it does nothing, and neither does editing the file to force color settings (it doesn't appear to support different color settings per monitor). I'd be very surprised if there wasn't some way to have nvidia-settings have these settings be persistent, but I can't find anything else in the gui.
In the newest version of nvidia, when I change the color settings in the nvidia-settings gui, they persist after the next time I reopen nvidia-settings, however they don't persist across reboots and don't appear to be saved in any config file (I'm making sure to have nvidia-settings save its settings to .nvidia-settings-rc).