I just bought the double pack a couple of days ago, but can't find anything in the manual or box about the first one being the director's cut. The boxart of Assassin's Creed II says 'Game of the Year Edition', but the art of the first game only has a 'Best Seller' sticker.
I'm playing through the first game now for a 1000G, though. Any idea what the differences between the original and director's cut are? As soon as I do or don't encounter them, I'll let you know. :-)