Having 2 Like buttons is kinda weird for me. How bout just one button, you click on the XF Like button and it not only does its XF duties but it then also works as a Facebook Like as well. Sending whatever information FB Like sends normally to Facebook. Of course this would only have that effect if the forum was FB activated and the user has a FB account and is logged in. The Like button would first complete its XF duties, then it would check if there is a FB account connected to the person clicking, if so then it sends it to FB, if not then nothing else happens.