Basically, players have been duplicating siege prints for wvw for profit on the trading post. The biggest source of duplicated objects are Omega Siege golems, which tanked in price going down to as low as 30 silver temporarily. The devs are aware of the duplication bug, but have not given confirmation if it affects items outside of WvW. Despite this, the bug exists and Arenanet is looking for help to uncover the true nature of the duplication bug.
You can help out by emailing additional information to *firstname.lastname@example.org*, please only send information if you have prior knowledge of the bug and do not attempt to find the exploit. There is a strong chance that you will get caught by Arenanet's detection grid if you successfully replicate the bug so don't risk it.
Despite the original reddit post's title, the thread containing the dev post confirming this has been removed.