You can copy an image to another display without having to render it twice..
Like the component out on my card let same clone the image of my monitor to my 37 inch HDTV, I doubt the gpu is rendering the image twice, but rather cloning it, as the name would suggest...
What if you wanted 3 monitors instead of 2, would it be so counterintuitive to have 2 GPU instead of 1...?
eh?
2 GPU's for 3 monitors instead of just a single card makes good sense to me, just like having an additional card for 2 monitors. Makes good sense to me if someone really wants to pay for something that doesn't give them twice the performance for twice the dollar.