Plot Item Left Behind.. how to prevent?

[vonzuben]

If you have a reward (Plot Item) given to a player and that player then logs with it still in their inventory, a little backpack-like looking thingie is left behind. That backpack can be “killed” and then the player doing the killing ends up receiving the item(s) that the other player who logged had. This is bad!

How can I prevent these backpacks from being left behind, or at least prevent them from giving the items to other players?