Hmmm... I don't think Double Enforcers can be spawned with W.O.R.M or any other mutator of this kind. You'd better remove it, use a single enforcer. I mean, the "double enforcer" you see there is just a "nomination" of the "akimbo priority", used for auto-switching. If you really want to spawn with akimbo weapons, you'd better get a mutator that does it, although it may not work with W.O.R.M.
The "blank bases" are probably wrong weapons. I mean, can you summon the weapons via cheat mode? When you type "summon botpack.enforcer" (for UT99, sorry, I don't play UT2k3/4) at the console, you create an enforcer... you should test the weapon strings in-game to check if the weapons exist or not.
The error you get when changing weapons can either be some wrong coding at some custom weapon or at the W.O.R.M mutator itself, so there's nothing we can do...