NullDupeFixer

Duplication is possible using Thermal Expansion inventories. 

Basically, a player can duplicate items by using a thermal expansion or otherwise non-disposing inventory.

Put a thing into the inventory, then break the inventory’s holder. Normally, this would dispose the inventory and drop the item. Sometimes, specifically on thermal expansion in 1.6.4, it does not. it instead breaks the block, drops the item, and leaves the inventory open. The player can then duplicate the item. It even works on backpacks.

This plugin fixes it. 

Config options available:

• Notify the Console
• Kill the Player
• Clear the Player’s inventory
• Just attempt to destroy the duplicated item

Compatibility: Currently works on API 1.6.4, but should be compatible all the way up the ladder. (Except 1.8)