Are you sure you are copying your original inv.* files into the 'inventory 2' game (overwriting the files there) before reloading it? After you drop the missing item and save the game, the files for the empty inventory need to be replaced with the originals from the save used at the start of the file swap procedure, after which the 'inventory 2' save needs to be reloaded, so the game will read the restored original inventory files.
