No one has to ED but if you prefer Brown, apply to Brown.
Have you been to either? Duke is GORGEOUS - I can’t speak for Brown but also know that your dorm is a (short) bus ride away (at Duke). I, for one, hate buses.
If you like Open Curriculum, maybe you ED Brown and if you don’t get in, go for a Rochester , Grinnell, or one of the NE LACs like Wesleyan, Vassar, or Hamilton (if not too small) and for a safety Kalamazoo - which is a PhD feeder for your majors. I think Wake also has an open curriculum option.
Don’t know about work hard / play hard but at Duke they love their hoops - but you will work hard - and hard and hard.
Personal choice but I wouldn’t go by school data. You are you. But yes, the likelihood of you getting in is little as is the acceptance rate. But no pain, no gain.
You’ll land somewhere great regardless.
I don’t know your long term plans but given the majors it will include school of some sort following undergrad.
As for other parts of your app - you be you - your ECs are great if you did them because you are passionate for them. That part of your profle is fine. Of course, no one knows how essays and LORs will be seen.