Bukkit

Basically if you use this kinda "key dupe" crate (i was messing around testing if it the way i put it to have a chance to get more keys worked , so i only had that in the config) :

http://pastebin.com/FBstN5MT

You'll start with  1 key and then you have 2 keys , then 3 etc , until you get 63 keys , then at 63 keys it'll stop stacking , and you'll have 63 keys in 1 stack , and 1 key in another slot , then no matter how many keys you use , you'll have 63 keys in 1 slot and 1 key in the other , and even if you get rid of every key and get a new one , you'll be stuck with 1 key , meaning for some reason , after you reach 63 key + 1 key in another slot , the crate will no longer give you 2 keys and use 1 up but it will give you 1 key , and use 1 key. You can just /cr reload to get it back in order doh

It probably won't be a very big issue since i don't think anyone would just have a crate that gives you 2 keys for the same crate , but if you have (in my case for my real config it's a 10% chance of getting another key) , So in my case , if someone happens to stack 63 keys , there's a 10% chance that it will break , and then nobody will get an extra key from the crate :v