not going to believe that until i see it. they might use less juice under ideal conditions, but in case of android where things are not very optimized, I am almost 100% sure it will use more juice.
There is a reason Moto decided to use 1930 mah batteries, and it is probably not to make us all happy with uber battery life. They are likely just aiming to match the battery life of single core phones, otherwise they would go for making the phone thinner with smaller battery (to be competitive with the obvious suspects)
And why in the world does Android need dual core? They need to get the OS sorted to the level of smoothness of iOS and Windows phone7 which both run great on a single core. Remember, the iphone has an 800mhz single core cpu with crappy graphics unit, yet it runs super quick and smooth.
The whole affair reminds me of lunatic approach that alot of laptop manufacturers used in last couple of years - stuff as much power as possible by using power hungry quad cores and massive video cards just to have the whole mess be bottlenecked by a slow hard drive and 1 hour of battery life.
These laptops did great in benchmarks, but a dual core with a low power video chip felt exactly as fast, but ran alot cooler and laster 5-6 hours on battery.