For the record, Duke does NOT expect its applicants to bring anything to the interview. Duke interviewers are told to not ask for resumes, essays, etc. So I’d recommend not bringing those.
I’ll echo all the other comments though. Slacks and a button down (“nice” jeans can be okay and I personally don’t judge, but I’d be safe and wear slacks) or blouse/skirt, be prepared to ask questions, show your enthusiasm for Duke, and be able to describe your past experiences and what you’d contribute to the Duke community.