Yes. Dan gets credit for third party sellers. I think the percentage is the same as well. The one real difference is since used books are usually pretty inexpensive ($5 to $10) to begin with Dan only sees small change. One book this month is only giving Dan $0.06.
On another notes school textbooks are usually over $50. Someone got a calculus book this month that will net Dan $10 or so. So If you are in College and you need to buy a bunch of Textbooks please use the associates page to do so