You'd have to throne a Bridge or something to pull that off... But the upshot is that you could run out the Duchy pile in the same move.
Not unless some Duchies were already gone to begin with, or a bunch of Estates were returned with Ambassador.
Hmmm, yeah, you would come up short. Actually, in two-player, you'd only get a mix of up to 5 Victory cards if you bought the first Estate with this move. You could trash your starting estates on a totally different turn to make up the others, if possible.