To duplicate items, start a Co-op game with another PSP and copy of the game. After finishing the game, you can trade. Give away all your items, then quit without saving. Your items will all be intact on your first PSP, and yet their copies will be available on the second. To duplicate money in a similar fashion, go to Vs. and offer all your money. Lose and quit without saving. You won't lose all your money, but the second PSP will still have it.