http://www.youtube.com/watch?v=PU_XlgpNTh8
4:45 - Joker: "Don't worry. I'm going to tell you where they are - both of them - and that's the point. You'll have to choose."
That's why I thought he was telling the truth about the addresses and the subsequent change was a continuity mistake. Joker was confident that Batman couldn't save both of them so no point in lying about who was where.