Yep, it most certainly matters. And indeed, it isn’t the law that allows someone who is born a dual citizen (at best) be considered NBC. It’s TBD.
Sorry, there's nothing TBD about it. It's a birther myth and nothing more. Another country's citizenship laws have no bearing on which American's are or are not natural born citizens. This idea is just another example of birthers trying to distort the law and the constitution to get their way.