I have a solution. But it is not that much recommendable. You may have to face some issues like localization if your Application has the Localization or in future if you want to change the label or if the new Styles of the Button control in the Application may change then you need to do some extra work.
Solution is Use Icon control instead of using Button and Create an Image( .gif or .jpg) like button with hard coded Two line label externally. Create Binary File rule and upload Image. Just include that Image as Source in the Icon Control.