Lets just say I found a REAL plat dupe a few months back and made 1000p+ on the crushbone server
I found it by accident after they added the offline merchant where you sold items through your house vault. It worked as follows.
You take the item you want to dupe and put it into your house vault. Once it is there you then put it up on the broker for whatever price you feel like, then after 11 min you set the value of your item to zero. The item will still be red, indicating you cant take it out of your vault. Leave your house then re enter and pick up the item out of your vault and exit house again. Now the fun part. Even thou the item is now in one of your bags it will still be up on the broker, so have an alt or friend waiting at the broker and get him to buy the item. Now you have 2 of the same item I did this with blazing eyes as they sold for 7.5g each and could be made into stacks of 20. You start out with 1 then 2 then 4 then 8,16,36,64,128...ect soon your dealing with stacks and i had 50 stacks at one time up on broker. Thats 75p in about 15 min Only risk was that any noob could get on the broker and buy my blazing eyes that I was selling for 20 copper, but the good thing was no one but my friend and I knew the true value of them. I also duped LOTS of master spells and armor as well as stacks and stacks of rare inks. Anyway I would have posted this when it worked but if I did then every man and his dog would have done it. I'm guessing I would have ended up getting busted or there being a major rollback of some sort. As far as I know I'm the only one to have figured this exploit out cus it worked for weeks + in the end they fixed it by accident