I had Biff appear as all three of the fishermen in the Ankheg map. I was trying to figure out the quest with the priestess of Umberlee and her feud with the fishermen in the village. I kept playing it trying different things and I had the AI for my characters scripts on and a couple of them nailed one of the fishermen as I was talking to them and then POOF! Biff appeared. It was quite amusing. I will have to try some other situations like the ones mentioned above to see if I can get him to appear.
Benthic