Found this glitch at the 2010 Club Penguin Fall Fair. It happens with the Member Prizes and shows up in your inventory twice!… To do this glitch you will need to buy something from the Clown Costume in the Member Prize Booth (make sure you’ve already purchased it with coins from a previous Penguin Style Catalog!)
See the rest here:
Club Penguin Fall Fair 2010: Double Item Glitch