It sounds like your video card might only enable you to load one set of LUTs (from one profile) at at time to run both monitors. You could look into the specs for that card to see if it supports two Look Up Tables. This is a common problem with Windows systems. With Win7 at least the operating system is capable of assigning different profiles to different screens. Even that requires some changing of settings:
1] Open up the Control Panel,
2] Choose Color Management,
3] In the Devices tab, click the Add… button to bring in the profiles for your monitors. You would select your different monitors in the drop-down box next to “devices” and then add the profile that you made for that particular monitor. Note which one you set as the “default Profile”.
4] Go to the Advanced Tab,
5] Click on the Use Window display calibration. (This will make sure that your proper profiles are loaded each time the computer is restarted.)
6] Click on the Change system defaults button to have these color settings be the same for all users of your computer (if necessary.)
I’m not sure why these identical monitors should give you such different results, but anyway a proper calibration and profiling (and proper enabling of profiles) should make the displays match.