I just checked to see if the mannequin dupe glitch still worked for me on the 360. I tried a few techniques to get it to work with no luck. I wonder it was fixed on the last update.
1. Head to your house in whiterun
2. Have Lydia follow you
3. Drop item(s) you want duplicated
4. Tell her to pick them up
5. Go back inside house
6. Leave house
7. Fast travel to stables
8. Fast travel back to Whiterun
9. Pick up your stuff where you dropped it (not all of it will dup all the time)
10. Have a snack and enjoy your new stuff.