Save the game at any point. Hold [Alt] and press [Tab] to switch to the Windows Desktop. Go into "My Computer/C:/Sierra". Right click the the "Sierra" folder. Then go to "Send To" and "Compressed Folder". You should see a folder appear that looks like a folder with a zipper. Hold [Alt] and press [Tab] to switch back to the game. Throw down the item that you want to duplicate. Save the game again and go back out. Go to your "Compressed Folder" and go into "Characters". Highlight everything in this area then hold [Ctrl] and press C to copy those items. Go back into the actual "Sierra" folder, then go into "Characters". Hold [Ctrl] and press V to paste those files. Switch back to the game. While holding [Shift], press 5 to reload your earlier save. Go into your inventory if it is not already displayed. You should now have the item you threw on the ground back in your inventory. However, the same item is also on the ground.