Two fucntions with same bindkey(cycling fucntions by bindkey)

I have 2 functions(say A and B) only differing in putting different widths of metals. The functions works well, but i want to assign only one bind key to execute them. For eg: 

I selected an instance by mouse click and press "Shift+1" so function A should execute. But if i press again "Shift+1" (instance being selected), then it should undo function A and instead function B should execute. Is there any way to do this?

so overall that means, if i select an instance and press "Shift+1" only 1 time, function A only should execute and if i press "Shift+1" totally 2 times, then only function B should execute.

I hope i made myself clear for you to understand.

Thanks! 

Leonardo Da Vinci