Pete,
Have you looked at them under black light? I looked at some of ours last night and discovered a couple of things...

1. some of the dice have "glow spots" (I think that's what Jeff L. called them), not always in the same spot

2. Most of the dice are "black" under the black light, but some are orangy-red. Two "pairs" weren't really pairs, since they were different colors under the black light. (One "pair" wasn't numbered, one "pair" had different numbers, but really close like E1241 and E1247, I think)