Cannot do that, I am afraid. I do not have alternative keyboards in my possession, with which to provide an answer ( Apple exchanged for a new board every time).
My experience is that, on every occasion, it was the keys adjacent on the keyboard that replaced what I wanted, or the letter m appearing instead of the "space" bar at the bottom - or sometimes the simple omission of the space between two words.
Hence my presumption that it is a membrane problem, allied to my poor keyboard technique!
I have gone through much of the "Settings" procedure, without finding anything wrong.
Apple insists that they have no record of similar defects.
I did not have the same experience with my previous iMac, with a more substantial/deeper keyboard
Hence the second part of my question: can you recommend an alternative to the current model of keyboard? What about a scissor-type mechanism? or a mechanical one? They seem (much) more expensive!
Many thanks for your interest.