No I guess there are no dupings out...
You can just raise the drops, i've did a hack which duplicates
the instances which are dropped... every monster drops something and the x5 amount of money which is usally dropped... It's just buggy and very very easy to detect by arena.net and players. bluntman should actually know it if he
already tried messing with gw. Its like the server send the information but then it will think its gone wrong and tries it again. (If your in a lag you can encounter that also...)