I'd rather do the following

{{ Form::button('Edit', array('type' => 'button', 'class' => 'btn btn-default btn-primary btn-switch', 'data-type' => 'edit')) }}
{{ Form::button('Add', array('type' => 'button', 'class' => 'btn btn-default btn-success btn-switch', 'data-type' => 'add')) }}
{{ Form::hidden('btnSelected', Input::old('btnSelected'), array('id' => 'btnSelected')) }}

You'll need some jQuery here, to populate the #btnSelected hidden input with the type of button selected.

$('.btn-switch').on('click', function(){
    $('#btnSelected').empty().val($(this).attr('data-type'));
    $('#yourForm').submit();
});

Now, how this works..

First off, you have the two buttons, but not submit, just plain ol' buttons. As you can see, I added the data-type attribute in order to detect what button was pressed.

After a button is pressed, the #btnSelected input is populated with this data-type attr I previously mentioned, and then the form submit() event is triggered.

From your controller, you'll just have to do

Input::get('btnSelected');

This will return you the type of button that was pressed.