There is a certain bug for modded minecraft servers that allow you to dupe a item in certain inventory blocks if you shift click a item out of a slot in that blocks inventory. This mod prevents shift clicking while in the inventory of that specific block thus preventing the dupe.
The values in the config.yml are not block id's or names, they are inventory names in order to get a inventory name a player must have the permission "antishiftclick.seestuff" once the player has that permission then they must click a block and open the inventory in it. When they do that they will see some text printed into their chatbox, copy this into the config to disallow shift clicking when in its inventory.
-antishiftclick.allow: If a player has this permission then it will allow them to bypass all shift-click blocking and they can do it in any inventory
-antishiftclick.seestuff: if a player has this permission then when they open a inventory block they will see the inventories name to add to the disallow list
