[dmjlambert]

Yes, 2 sets of contacts, at different depths of button press. It appears to be most useful to detect how fast you are pressing or releasing the button. I can have the Arduino recognize slow press followed by slow release, or slow press followed by fast release, or fast press followed by slow release, or fast press followed by fast release. Partial press and release is also possible, but a little harder to reliably do with my finger without accidentally hitting the deep contact some of the attempts.