If you mean dual monitors, your computer needs to be able to support 2 different color profiles for your two monitors. If your computer doesn't support it, it doesn't matter if the color calibrator does.
If you mean dual monitors, your computer needs to be able to support 2 different color profiles for your two monitors. If your computer doesn't support it, it doesn't matter if the color calibrator does.
Yes, they do. Although with the Spyder 2 Express software, you have to calibrate one monitor at a time and rename the profiles by hand in the Finder. It's also useful to change the profile description via ColorSync Utility.