and then at the end you had to leave for good...thus a couple of years after that fallout 2 happens
It's actually quite a bit more than a couple of years... Unless the Vault Dweller, of course, the Vault Dweller had children, and then had grandchildren that grew up to be at least 16 years old in a couple of years.
I think the T-51b armor in the fort is also better than the winterized one from O:A.
They have the same stats, because, for all intents and purposes, they are the same armour. In fact, if one had to be better, than the winterized T-51b armour would be it, since it's in better condition than the regular T-51b armour.