Marshall also dished off 10 assists, while Tyler Zeller contributed 19 points and 10 rebounds for North Carolina (27-4, 14-2 ACC), which avenged its last-second Feb. 8 loss to Duke.
The Tar Heels blew a big late lead in that contest, but made sure not to do so again Saturday after jumping out to a 24-point halftime lead en route to their seventh straight win in the regular season finales for both schools.
The Tar Heels enter next week's ACC Tournament as the top seed.
Miles Plumlee accounted for 16 points and 11 rebounds for the Blue Devils (26-5, 13-3), who saw their own seven-game winning streak broken.
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