I previously used a MacBook Pro 2016, and I had problems with the b where the key produced a
bb about one third of the time I hit the key. After getting it repaired, several months later, the same problem started with the N key.
I now own a MacBook Pro 2017, and I have the same problem with the M key, but maybe with an occurrence of only one in forty, which makes it much harder to demonstrate.
It's always the same zone on the keyboard, I was wondering if anyone else was experiencing the same problem and what they did to fix it?