Wouldn't that be the same as extending your contract for an additional year? If you have a 2 year contract and you upgrade early then that renews a 2 year contract so that would add 1 year to the end of the first contract. Or does it add 2 years onto the back of your first contract (which would expire in one year) making your contract length 3 years...that doesn't seem right.
Sorry, I probably should have specified that if you do an early upgrade in the middle of a 2 year contract then you add on an additional year. My bad.