As the title says, I was checking my pc, and found 2 graphics cards.... First, my R9 390, then I found "extension Graphics Adapter", what is that?
Next step - flick through values in that combobox until you see the name of inf-file. Go to that inf-file in Windows folder and paste its content here. (If it is very long then you can place it within SPOILER tags).
It's a virtual display adapter which has been installed with some WiDi/MiraCast solution/dongle //Yep, most probably EZCast dongle