So you guys are saying that vpin doesn't do double buttons, but pinmame does, and there is a way to tell vpin to activate the extra buttons? (I suppose that makes sense since it is really a table editor). Slowly it all starts to make sense... or does it?
It sounds like Zakk may have gotten his answer, but I'm going put an answer out here for others.
You can have more than one set of flipper buttons in Visual Pinball. You could have as many flipper buttons as there are keys available on the keyboard. Visual Pinball allows the table creators to use any key to do what ever they want.
There is direct support for severlal predefined keys. (Left and Right Flippers, Plunger, Coin, Tilt Left, Tilt Right, etc). If the tabl creator uses these predefined keys, then they can be changed easily through the Preferences/Keys menu.
The table creator can also use other keycodes for additional functions as shown in EdgeDamage's example above. When they do this, you need to edit the script to change the keys because they will not show up in the Preferences menu.