1. level 30 or level 40 character - No class change yet
2. Items to duplicate
3. 2 Personal computers or dual logins -
1. Create a level 30 character - Do not do the job class change yet. Lets call this character - "Lowbie"
2. Fill Lowbie's bag until you only have 15 slots left.
3. Move Lowbie to the Race Manager ready to accept the job change.
4. Move the character that has the items to be duped. Lets call him Highbie.
5. Perform the job change but do not accept yet the rewards.
6. Trade and lock ( but do not confirm ) 15 items to be duped from Highbie to Lowbie.
7. Accept the job change rewards. And then Lowbie confirms the trade.
8. Lowbie will get an error, but that is normal.
9. Due to the error the items will be back with Highbie. Lowbie needs to reconnect to be able to get the items.
10. There its all duped. Rinse and repeat.
*** this dupe does not work in the official servers ***