You can duplicate any number of items and give them to a character just starting out in the campaign. To do this, you must first have a saved game file that has the character with the item that you want to duplicate. Start a new game with up to four characters and import the character with the item desired to be duplicated into each of the characters (up to four). Give all of the items to be duplicated to one of them and save the game. Then, create a new game and repeat the same procedure; but this time use the character from the newest saved game which should have multiple items already. Note: To save memory card space, just keep saving over the duplicating file. Continue doing this until the number of items duplicated is reached. Start a new game creating the character you want for the mission, then import the character that has been duplicated and give the items to the character that is actually being created for a game. Finally, create a new game and import the character that you created and then gave the duplicated items to in order to start the game with whatever items desired. Note: This can also be done to generate more money by selling the duplicated items instead of keeping them with the character that was created for the new game.
This trick requires at least two controllers and enough space on your memory card for two files (about 800K). Go to "Create Game" under the adventurous level, and choose how many players you want. For example, if you have four controllers, choose four players. When you get to the player selection screen, import the character who has the items to be duplicated to every player and start the game. You will now have copies of your character. Have all but one of your extra characters drop the desired items. Then, pick them up with your primary character (that did not drop the items) and save the game. Then, exit the game and go to the main menu. Start a new game on any difficulty setting. At the character import/selection screen, and import the character that picked up the dropped items. You have now duplicated those items.
This trick requires all eleven Bloodstones. Having a keyboard or microphone is also desired, so that you can tell other players what you are doing so that they will not pick up what you drop. When you get to the end of the Bloodstone Passage, the game auto-saves. Do not go in yet. Enter your inventory and drop a few items, such as eight Perfect Bears or some gems. Go into the Twisted Nightmare and intentionally die. The items will remain on the floor where you left them and you still have the bears that you had before you dropped them, because the game saved when you had them. Drop eight more, go in, and die. There should be sixteen on the floor. Be on the safe side, and do not drop all twenty five items. If you pick up the items then die, you will lose out -- the game does not save again after that first save. Do this two times and exit the mission, just for caution.