Maths or Further Maths A Level for Economics at LSE

I want to be offered a place by LSE for a degree in economics (or at least, an economics-related degree, I'm not sure if I want to do a combination one but it's unlikely). I'm starting A Levels in September and am currently doing Maths, Economics and Psychology. I'm considering upgrading maths to Double Maths, but the required grade on the LSE website for Single is A*. They do not say if Double differs from this. If I take Double and get just an A, will this effect my chances negatively compared to A* in Single, not have any effect or still keep the positives of taking the extra content? Thanks!