Making all NPC IDs even
 

I am using GeorgeS's tool for D2 style loot, and I noticed that it doubles the lootdrops for all monsters with an odd ID, so I was wondering if there is a simple way to make all NPC IDs even because I don't want some monsters to drop 4 things and then others drop 8. Also, maybe there is a way to remove 2 lootdrops from each NPC with an odd ID using mysql.