Free Republic says in both the lead and the story "say the odds or finding a half-and-half lobster are 1 in 50 million to 100 million."
While looking for the story, it seems that another one was caught in Nova Scotia the week before that was not only 2 colors but 2 sexes. The other statistical problem is that they mean that 1 in 50 to 100 million lobsters are half-and-half colored. The odds of someone finding one would vary depend on how many lobsters he catches. The odds of my catching a lobster of even one color are 0.