Controllers behaviours

Kenton Killamix mini + Audio File Player
press button 1 - lit green - (Note on) > Lane 1 Play
press again button 1 - “un” lit green (Note off) > Lane 1 stop
So, Is this a trick? a way of that it just works!

How many buttons are there in the image below? only one?

Actually two!, one on top of the other (using macosx zoom to a pixel)
the green one for Note on ( lit green-play)
and another the red one for stop, inversion ON