Using LibKeyBound or InfiniBar to set the bindings, no, it's not possible. However, it is possible using macros.
Get the name of the button by placing the cursor over it and typing:
For the sake of example we'll say the name of the button is IBSecure_Main1. Now make a macro that says:
Now use SpellBinder, BindPad, or some other direct-binding addon to bind the macro to your desired second binding.
Obviously this will use up a lot of macro slots, and may be problematic if you need to do it on multiple characters.
thanks mate, that helped