Mr. Laser Beam wrote:
Then again, there's no proof that the "Dax" in the mirror Jadzia's name was the symbiont. It could simply be a last name. Perhaps she believed the symbiont to be dead, and chose its name for her last name to honor it?
Or maybe, like I said, she just didn't feel like correcting Sisko when he called her that. She didn't like him much at that point, anyway.
I'm not sure if this counts as proof, but the ST collectible card game card for Mirror Jadzia has text that says she's a joined trill, and her name is Jadzia Dax. I don't see any proof or even a hint or suggestion that Mirror Jadzia wasn't joined with Dax.