though you can surely find a school that offers both, it seems that the really good schools do not. you can always take graduate courses in either, but if the paper is what you are after, you will have to sacrifice to get it. really, i would advise getting into the best school you can and taking some classes in both. given what you would gain from such an endeavor, you would not need any paper to distinguish you from someone who has not taken the extra classes. also, why the masters? the really respectable programs (mit, caltech, princeton, columbia, chicago) do not even offer a masters except by special request, it is just expected that you are in it for the big one. i hope i have helped. good luck with whatever you choose!