What will happen when a werelizard bites a dwarf that is already infected by a weregoat? Does it matter if the dwarf is in weregoat form during the biting?
Having a were-curse prevents the target from collecting any other were-curse, among other things. So... nothing besides normal bite damage.
I've checked the raws in /raw/interaction examples.txt, the were-curse definition cannot apply to: vampires, not-living creatures (aka elementals and bronze colossi), supernatural creatures, other were-cursed, and people who were cursed by a mummy. Actually, all curses - were, vampire and mummy - exclude each other. Pity.
[INTERACTION:WEREBEAST_CURSE] [I_TARGET:A:CREATURE] snip [IT_FORBIDDEN:NOT_LIVING] [IT_FORBIDDEN:SUPERNATURAL] [IT_CANNOT_HAVE_SYNDROME_CLASS:WERECURSE] [IT_CANNOT_HAVE_SYNDROME_CLASS:VAMPCURSE] [IT_CANNOT_HAVE_SYNDROME_CLASS:DISTURBANCE_CURSE]