Manual

Video Driver Controls
C - 26 Attaching Other Displays - Devices (Charms Bar)
C
5. You can configure the displays from the Multiple Displays menu.
Duplicate these displays - Shows an exact copy of the main display desktop on
the other display(s)
Extend these displays - Treats both connected displays as separate devices
Show desktop only on 1/2 - Only one of your displays is used.
Figure C - 21
Screen Resolution
Multiple Display
Options