Arrow keys intermittently doubling

[cyrille de brébisson]

Hello,

"but in my testing I see the behavior fairly often when tapping the keys at roughly 0.5-second intervals"

Ha, this might be the key to the issue (pun intended
I would venture that the key release is not detected and that when you press the key again matches with the moment when the calculator tries to see if the key is still pressed, and it detects it as still pressed, and repeat.

This would not be a HW problem.

Cyrille