Dupe. Use at own risk. Comes from gold-world-of-warcraft.com
Go to a vendor who sales limited objects (patterns or what ever). Raise up your ping to 180-210 (or maybe higher), by downloading some, or run a program. Buyout the limited objects down to 1 and than right click on the item as fast as you can.
You have a chance of 90 %, that you get the item 2 times, paying only one. This chance is given, too, if the vendor has only 1 of them at the beginning.
Find a vendor that is selling items.
Make sure he only has a limited supply of an item.
Use something to lag your system, hit the screen shot button a ton
Buy out the item down to only 1 of it left.
Right click the item as fast as you can.
You have the chance to get 2 items instead of one.
Note: I got it to work so far twice with me. Its hard and I’m assuming the chance isn’t 100% but it can be done.