so one for all can exist ,but def not rengar(kha) ,def not kha( rengar) skin?cause confusion ?

As a fan of the Definitely Not skins, that would be fun to see Rengar or Kha'zix with an oversized mustache and silly glasses.

Oh wait. That's not what you're proposing at all. You just want them to look like eachother. How are you not seeing the confusion this would cause for people?

There's a big difference between One For All, a for-fun game mode where everyone is the same champion (picking different skins helps figure out who is who btw) and purposely misleading people in normal and ranked games by looking like a champ who wasn't picked.

all for one is an isolated mode that one has to queue up to play if they choose to.

a skin can be selected by anyone in any game mode and can cause confusion in situations that matter. like ranked. or even normal draft. or in new player games where they still dont really know names of champions they only know that the robot looking thing pulls you in.

...I hope English isn't your first language..If it is though, I feel obliged to say i'm deeply sorry.