How do you get doppelganger on devil may cry 3 original not SE ?

i have it on ps2

and is doppelganger 2 playerHow do you get doppelganger on devil may cry 3 original not SE ?
where did u reach u need to get to a certain level to get a doppelganger u need to fight this giant flamed devil which is so easy and yes when u turn on the doppelganger you can press start on another controller which is the doppelganger and so u have 2 player but if u turn off the doppelganger 2 player mode turns of