I won't comment on the 16 cores CPU, because having 16 cores isn't a good indication of processing power. As I said before, single thread or core performance multiplied by the number of threads or core gives a better indication.
If MS is going for dual GPUs, with two GPUs that are mirror images of another, I would imagine it's to get around the financial constraints of having dies sizes great than 300 mm^2 in a console.
Manufacturing 10,000 200mm^2 gpus would be cheaper than 5,000 400mm^2 due to better yields rates on the smaller die, and if they can get two smaller GPUs to perform close to the large one, they'll save a lot of money right of the gate. They easily combine the two when the node process allows them too.
They're probably pushing the 720 to be a graphical monster (better than PCs), if that's the case.
The second theory is a set-up like the rumored Orbis set-up, which I think isn't going to be as cutting edge as the set-up above.
The third is two SOCs, which I really can't make judgement on.