You look to be competitive for either college. Note: applying ED to Duke this year might be slightly more advantageous than Brown as Brown saw a 8% increase in ED apps last year (up 8%) while Duke’s ED apps were down (-11%). With the financial uncertainty of CV-19 and many students unable to physically visit college campuses this year, I would expect that the number of apps will decrease and result in higher ED acceptance rates for most colleges. My guess is Duke’s ED acceptance rate will be 25% this year and Brown 20%+.
Make sure on your app that you really “tell the story” of how you will make each college (and your larger community) a better place (e.g. global warming). You LOR and ECs shoud try to tie into this theme, if possible. You need to distinguish yourself from your peers as most of the applicants will be strong contenders.
Good luck and keep us updated!