Update: after about 1 hour of tests I have discovered that even my first MacBook Pro has the issue! I had not noticed this because it's on the 9, a button that I have not used very much lately. I have also noticed it on the 7 and 8, but much less and very sporadically. Yes, I can confirm that heat seems to be make the issue much much worse, but in my tests, I have found the issue very inconsistent and sometimes difficult to detect. Sometimes the keys seems to be working just fine, and you think you are completely crazy, sometimes they do the noise every ****ing time you press, it's maddening.
Since both of my MacBook Pro 15" 2016 have this problem (albeit on different keys), I am really disheartened. It will be very difficult, if not impossible, to find a replacement without defective keys. I am considering just returning both and don't try again until the next refresh. Possibly with 32GB of RAM please!