So the kid was a copy cat?
No, the kid was the original. Much of this episode was from the event 6 years ago. You could tell the difference between the two time periods because Serano had black hair during the flashback scenes and white hair in the present.
But the kid also wasn't responsible for most of the crimes committed by "the Laughing Man." That was a non-existent entity created by Secretary General Yakushima and his political allies to serve as a scapegoat for their white collar crime.