I don't think the card is to compete with the hopefully soon coming AMD HD 6990 for the fastest Graphic Card on the market.
Probably the main purpose of the EVGA dual card is to enable Nvidia surround on single card.
My speculating about the above is based on the Hexus article
that the card will cost less than GTX 580. I don't think EVGA would sell faster card than GTX 580 for less money.
Although we couldn't tease too many details from the reps on hand, we know it'll be based on two GF104 chips, carry 2GB of memory, support three-screen surround gaming out of the box, all the while costing less than a GTX 580
Just in case the Hexus article about the price is mistake and the card is to compete against the HD 6990, I prefer the 4GB GDDR5 the HD 6990 is supposed to have.