But...but...but they said the reason I couldn't play offline...the reason I had to put up with server lag...the reason I had to put up with server maintenance was to prevent item duping. Surely this is all just a bad joke, right? Right?
It's not duping and it's been secretly patched already.
It's a rollback, so you could rollback to before you crafted if you didn't like the items you got. Once it became widespread today on sites like reddit and bliz forums they hotfixed it fast.
The method was already posted on multiple underground sites.
I'm not going to go into detail since it's been patched, but it basically took advantage of waypoints, and the fact that when the host player leaves the game without getting a quest update the game disconnects for everyone, acting as if the trades and crafts never took place.