Comment by Staaaa on Killua.

@Killua. I think that it is his actual past life as he was joon's first doppelganger he made on his own also i could be wrong about all this but joon made him thinking about his favourite idol that's why he has a similar face to that idol ( who is alive) 
Well i could be wrong about everything but i am a hundred percent sure that those are the memories from his actual past life before he died and before his soul was collected by the company that makes doppelganger....