I'm putting this in rumors because it isn't clear from the marketing materials. I have read that the 7DMKII sensor is brand new and redesigned from the ground up. But, when I dig into the details, the only changes they point out are redesigned micro-lenses. That's not quite "redesigned from the ground up".
So there are a few possibilities...
1. Canon redesigned the sensor completely, but is only pointing out the changes in the micro-lenses. This doesn't make sense. Canon fans around the world would've cheered and sang cum-bay-yah if we had a fully redesigned sensor. There is no reason for Canon to hide it.
2. Canon only redesigned the micro-lenses from the 70D, but is hinting they redesigned it. The micro-lenses needed a redesign, but that didn't make it into the 70D. So 7DMKII buyers may benefit from this. More photons = better images. But, this is a bit dishonest on Canon's part. They know they are behind in the sensor race and pretending to redesign a sensor doesn't bode well for an industry leader.
So... Based off the initial reports, I'm going to say they only redesigned the micro-lenses; and the "redesigned sensor" is a lie. Since I'm pulling for Canon, I'd love it if someone could post links to help clear this up.
Canon knows they are behind, but I'm surprised by what I see as an outright lie. If it's the same sensor, say it is. Don't pretend. I'd love to have this thread clear this up. Even if it takes until launch.