I also disagree with the argument that Duke is a better brand than UNC. They're both Top 20 b-schools with national recognition. I live on the west coast, and I'm sure almost everyone knows that UNC is a top-tier school, both undergrad and grad. If you are planning to work on the west coast after graduation, I think that, regardless of the school you pick, Duke or UNC, you'd be left with the majority of the job-finding legwork. There aren't too many companies flying to North Carolina to recruit when UCLA, USC, and Berkeley are all in one state.
If I had to choose between UNC and Duke, I would definitely do my homework. UNC may be of slightly lower rank than Duke, but if you're picking a school solely based on brand name, you're doing yourself a serious disservice. People on these boards are so caught up with brand name, and often forget the most important part of life-- happiness. I'd rather spend 2 years at a fun school with inspiring peers, than a great school with a bunch of dial tones.