They should have used a different skeleton and different geometry. In other words, the developers in "Haven" simply changed the files and partially used the same IDs as in "Fortress," so I just made copies with different file names to avoid conflicts!
P.S. By the way, this model has a MEGA-BUG: the hero doesn't have a sword on the adventure map, so don't download this fix yet; I'm adding the sword to the scabbard now!