My keyboard (numpad) overwrites everything
I was having the same problem with my HP SK-2028, and I found something that at least sort of works. If you turn on 'slow keys' in the accessibility settings and play with the settings a little bit, eventually there is a sweet spot where you will be able to type your numbers in, albeit a little slower, but at least it will function like it is supposed to. I found a spot in between the first two bars so I don't have to type tooooo much slower than I usually would. You can press alt+command+F5 to bring up the quick-accessibility options pane to quickly deselect or re-select slow keys as needed

-Amy