I have 2 monitors and each are plugged into a dvi port on my videocard.
HP 2011x HP 20xi
I downloaded and installed each driver from the HP website, restarted, same issue. Then I downloaded the HP Driver Assistant which just redownloaded the above 2 updates.
Windows 7 also detected an optional update and I installed that too (which for some reason cannot be uninstalled via Programs and Features - View installed updates)
HP - Display - HP Pavilion 20xi IPS LED Backlit Monitor
The monitors are stuck mirroring each other and when I try to detect the monitors, only the HP 20xi will appear and one other thing that's strange is that Windows thinks the monitor is hooked up using a VGA port.
HP Pavilion 20xi IPS LED Backlit Monitor on Standard VGA Graphics Adapter
Also the monitors can both be detected on Linux Mint.