Duplicating displays

[Mothership]

Hi all, I currently have a Dell IPS and Panasonic plasma hooked up to my computer. I normally use the "extend displays" setting, but it would be easier to just duplicate the screens. If I do this, and start playing BF3, will this mean extra strain on my videocard, as it has to display the graphics on 2 screens, or will it not matter at all?

 

[weird_dave]

It shouldn't matter as it's not rendering to both screens, the hardware doesn't do anything extra. It's better than extending too

edit:

Test it with a benchmark