It's happened with some older emulators too.
I have no idea why.
When Kitsune first released the patch, it was suspected to have to do with the hack I made to disable the CHR-ROM protection check on the title screen.
(there was an INC $21 that set the anti-piracy flag, I replaced it with an RTS)
Nestopia was the one that basically killed mapper 23, replacing it with auto-detection for known original games and breaking ROM hacks (such as my translation for Dragon Scroll). I'm guessing KD was another 23 game?