Well my last bug post found comments (albeit few) that stated he was dropping 2 items in each case. Didn't see anything suggesting 1 or 0 drops. Only comments with 2 drops were found.
See here:
http://www.project1999.com/forums/sh...hlight=Dartain
Problem with him is due to his location in the Hole and behind a locked door there is very limited info on him.