(NOTE: This is not over LIVE. This is with two controllers.)
1) Make sure you have at least one Rotten Egg. (After you have done the exploit, if you permanently keep a stock of 45 (5 for each inventory slot) you can make the 90,000 credits one run (remember to keep 45 eggs for the next duplication.))
2) Go to Chapter Select and pick any of them (2-1 is what I used because it has no cut scenes)
3) On the inventory screen, take everything off but the egg.
4) Ready up and enter the game.
5) When the game is loaded, press Start on the second controller to join in.
6) After selecting the storage device, you will be back at the inventory screen. From here, give Sheva (the second controller) your Rotten Egg(s). Ready up and enter the game.
7) When the game has loaded, have Sheva (second pad) give Chris (you) the egg(s).
8) THE MOST IMPORTANT PART - After you've given the egg over to Chris, press start on the first controller and go to Quit. On the first prompt, press A (Yes). Now, both screens will say "Do you wish to overwrite your inventory?" For YOUR controller (Chris), select Yes. For the second controller (Sheva), select No.
This is an absolute must, or the exploit will not work.
9) Go back to Chapter Select and load whichever level you want. You'll see Chris has an egg. Ready up and join in on the second controller again. You'll see Sheva has an egg too.
10) To continue multiplying, give Sheva your egg from the inventory screen, and ready up. Have her give you both eggs in game. Then follow step 8 again. Rinse and repeat until you have 45 eggs (5 per slot) on both characters.
11) Once you have 45 on both, have the second controller join in, but SELL all of Chris' eggs. You should get $90,000. After this, ready up and proceed as normal. Rinse and repeat until you have as much gold as you want.
(If you need a Rotten Egg, they are dropped randomly by majini after chapter 4-1.)
UPDATE:
Video added (Watch in HD)
Resident Evil 5 Exploiting Duplication.
