Which GPU set-up is better?

I'm currently in the market for a new computer, and I'm tossing around the Lenovo 510y gaming laptop. It has a slot that allows for a second NVIDIA GeForce GT755M GDDR5 2GB GPU for added performance.

I've seen that for about the same price I could also afford different computers with the NVIDIA® GeForce® GTX 760M 2GB GDDR5 VRAM.

Which set up would be better? I know that the GTX 760m is a higher quality GPU, but would it out perform two GT755Ms?

Added (1). I'm also looking at a laptop with the following GPU: 3GB GDDR5 NVIDIA® GeForce® GTX 770M w/NVIDIA® Optimus™ Technology

Guest

3dMark benchmarks are quite accurate. The following page is a list of GPUs and their 3dMark scores so that you can see an apples and apples comparison. Just look up something you know and can compare it to to get a base line.
http://www.futuremark.com/hardware/gpu

The GTX 760M scores 3480 and the GTX 770M scores 5150, or approximately 47% better.

To see how much you really need so that you aren't over-purchasing would be to look at the recommended hardware for the most demanding things you do and compare their benchmarks to those of the hardware you are considering.

http://www.futuremark.com/hardware/gpu/NVIDIA+GeForce+GTX+760M/benchmarks

tumbleweed_biff

Get the laptop with the GTX 760 or even better, the 770… Any of those two cards will opt perform a dual GT755… The gtx series were actually made for gaming, the gt series were not really.
You can email me at m_techno@rocketmail.com for more assistance

Techno