Go into the hamlet and drop the items you want to duplicate. Leave 
the hamlet and exit the game. Look in the "adom_dat" folder and go
into the "temp dat" folder. There will be two files there. Copy 
them to another folder then resume the game go back into the hamlet.
Once there, get your items and leave again. Copy the temp files back
into the original directory (answer "Yes" to overwrite all). Then, 
go back into the hamlet and the items will be laying there again. 
You can also transfer items to other characters by doing this.