More Blade Runner

For those wanting a detailed breakdown of the differences/changes in Blade Runner: The Final Cut, take a gander at this article on aintitcool http://www.aintitcool.com/node/34373. That man sure knows his Blade Runner, although some of the added violence in the Final Cut was, I think, always present in the International Cut of the 1982 version which was, of course, slightly different to the original US cut (wow, that sounded very anal). But something that occured to me for the first time watching the latest version was the fact that Batty calls Deckard by name during the climax in Sebastian's apartment. How does he know that?