Bukkit

What version of QuickShop are you using?
B: QuickShop 4.4 for CB 1.5.2-R0.1
What version + build of Bukkit are you using?
Spigot 1.6.2 build #1031

What is the issue?
Zombies steal Display Items hovering over QuickShops. The Display Item itself appears again over the chest after being stolen but the zombies gain items.

I noticed this very funny behaviour yesterday and thought I'd report it in case you weren't aware of it. I tried killing the zombies and so far I haven't gained any of the items ... so it might be a non-issue. But it definitely needs more testing because in the worst case scenario people could use this to dupe highly valuable items by making a QuickShop at some dark and dreary zombie spawner.

A quick fix would be to - obviously - disable the Display Items, but personally I love those little things.

Could you look into this? I will make some more tests today on my server and see if I can actually dupe items. I'll will add my findings to this bug report.

This is basically because Bukkit provide us with no way to detect entities picking up items, it's perfectly safe though.

Mobs will pick items up, die, drop the same item. The item has 0 count (thus cannot be picked up) and there is a listener for players picking up the item to prevent it. So it should be perfectly safe.