This is a bit of an odd request and somewhat related to #26 and #17 .

Currently the ability to specify mob drops on death is somewhat limited. If you would like to have chances for a mob to drop multiple items you have to create multiple rules. While this does work it ends up increasing the overall amount of loot dropped instead of dropping one thing or another it's a chance for both. The more items you add the more stuff you'll eventually get. I think a good way to handle this would be to attach a loot table to the mobs death drops rather than an item, using Minecraft's native item generator to handle random chance and the like.

Failing that, if you have an alternative solution to adding exclusive random item drops, I would love to hear it. I'm currently trying to create a system where monsters in Lost Cities have a chance to drop salvage that the player can turn into resources to encourage a bit of exploration over strip mining. GrimCo/grimco-rd1#1

Will consider this but later