I like vintage gaming, and these switches are new to me. A double layer micro tactile switch often used in light guns. Meditating on applications. This seller is excellent and well regarded in terms of product performance.
Any other interesting switch finds?
Edit: better link
That seems like a very cool thing for creating more interactions with a single button, however, I would think the prop would need to be aware, since you can’t push the second button without also push the first button.
Also perfect for a double-barrel shotgun prop. 
If a prop had a hold button 1 + press button 2 (like lightning block) and this switch keeps the first circuit closed as the second is closed, maybe you could place a dual button input on a single button.
Boomstick is a great idea!
I recall seeing a hilt with a control box slider-switch that only allowed pushing one button at a time… two of these would allow you to have Pow+Aux or Aux+Pow. Maybe overly complicated…
Of course you could make NUM_BUTTONS 4 and go crazy in a prop.
I sense an opportunity for learning. Ordered 10.