Simple solution. Speak to the guy, explain that our comrade who has pass on used that handle and as a community we think it would be great if he, the new player, would willingly change it out of respect. Any reasonable person would agree to that.
If he disagrees with that then most likely he has chosen the handle for attention and in disrespect of the original. At this point anyone who takes exception to the behaviour can perma-squelch him and reduce the attention he can gain from the stunt.