Well the last I heard... developers found a way to detect which items were duped using their individual IDs. I know this is what they did at the end of DEKARON EU, meaning all dupers got banned, and all duped items deleted.
I'm sure there are still people out there clever enough to find a way around this. I just haven't had a chance to look into it any more than that. The obvious ways are all not working now. (Maintenance / forced disconnect). But I'm no expert game hacker so...
...all i'm saying is that i would be careful. Last time duping became ridiculous and I'm pretty sure 90% of people who did it were punished
-Daniel