Duke, UNC-Chapel Hill, UNC-Charlotte, UNC-Greensboro, NC Central University, and NC State University have cross-registration arrangements, although the distances between some of these campuses may make in person course attendance during the regular academic year more challenging.
Additionally, Duke and UNC-Chapel Hill have a full scholarship program (Robertson Scholars) where the arrangement is more formalized, with students doing a one semester “campus switch” during their sophomore year. Here: https://robertsonscholars.org/