Yeah, I realized got the functionality mixed up with the ‘Game Piece Layers control’ button, which toggles different layers on and off. But that doesn’t include 2 button images. 
If it doesn’t have to be on the toolbar, you could just define an unmoveable game piece in an at-start stack, off to the side of the board someplace. Then use a Layer trait on the game piece to define a +0 level and a +1 level.