I think the best adage to go by is "if you enjoy it, then do it." It certainly won't look "bad" if you have a double major in anything. Some of the "top" schools might take offense if you don't get an "A" in every single science and science related subject. But, people get into medical schools with 3.0 GPA's (even lower sometimes) and 25 MCAT's. Have some fun in school, do what you enjoy most, and do the best that you can in every subject. If you do find your science course grades slipping because you have too much on your plate, you may want to ease back on the classics studies (if you really want to be an MD that is instead of a classics professor or some other equally enjoyable career). I hope all goes well. Good luck with the rest of your studies.