I've ran into an issue where Zombie Pigmen and Zombies are dropping their (normally spawned in or picked up) held items. I've set OtherDrops to prevent the dropping of Gold Swords on Zombie Pigmen, yet still received a Gold Sword. Below is a pastebin link of the successful rolls to prevent item drops (still received Gold Sword), as well as a successful roll for only Rotten Flesh (yet still receiving a Gold Sword):

http://pastebin.com/eB91e3sv

I'm running the Bukkit Beta 1.7.2-R0.2 build.