Well only if you were to buy the 4GB versions, but yeah. I guess the single 690 would consume a little less power, but it would also deliver less performance so I don't really see the point of this card at this price, unless you are low on PCI-E slots or something.
660ti and 670 confirmed?
http://wccftech.com/nvidia-geforce-gtx-670-geforce-gtx-660ti-final-specifications-leaked-reference-pcb-gtx-670-unveiled/
http://www.maximum-tech.net/nvidia-geforce-gtx-670-release-date-confirmed-12397/