Dynasty Warriors Vol. 2 Hints for PSP
Here's how to get 2 cao caos in a battle. Using Wu forces, Defeat both Cao cao and Liu Bei in "showdown at chang jiang" You'll Unlock Cao cao as an officer(lv21).
Next, in either of the 2 modes, play stages with cao cao in it(Yellow Turban Rebellion, most of the stages if u're using Wei Forces).
You'll see you're officer cao cao fighting and randomly cao cao will invade and you'll see 2 identical cao caos(except for the colour of their names) fighting alongside!
You may do the same if you want cao cao fighting against cao cao. Have fun laughing =P