So you want your snake-bodied demon to use multiple shields instead of a bunch of swords in your GURPS game? Or some clever munchkin of a player says, he, I'm going to fight with two large shields?
What happens then?
Luckily, Kromm answered that on the SJG Forums here:
Re: 4 arms, 2 large shields, bonus to defense ?
This does bring up the question - what is the best second shield? If breakage isn't a concern, then cost and weight are - you'll want a smaller secondary shield. But then again, that leaves you with a lower DB in the side hex on that side. Ideally you'll want two equally effective shields to cover you with the same level of defense from all angles.
You may also notice that I presciently gave the Ebony Death Goddess two shields, and while she's got two Blocks (and thus two multiple-defense cascades) she only gets the 2 DB from a Medium Shield, not some improved amount for extra shields. So she's Kromm Ruling Compatible as written. That Cross Block he mentioned, though, could give her yet another option for fending off heavy attack.