Bug - 2 instance Lol (even 4 sometimes) run in the same time

So it happens right in the middle of a game ... An other instance of LoL start running for no reason ... And now every time I launch the client the same thing happen ... I'm on a MacBook Pro under macOS Mojave 10.14.2 ... The problem is when it happens i m playing with 10-20 fps wich is a huge pain in the *** :/ Anyone can help ? Or give advice ?

I already try to uninstall et install League again it doesnt worked ... I already change the video set up to try to increase the fps by "downing" them ... but nothing worked so pls ... HELP ME !