Somebody on this site just asked a very similar question (and it’s still on the first page…http://talk.collegeconfidential.com/duke-university/1810502-act-vs-sat-score-submission.html). No, you do NOT have to submit your SAT IIs. You can submit your ACT (w/ writing) and SAT I scores and are good to go. (The SAT I score being “optional” because you already submitted the ACT. But if you did well on it, might as well submit it too.) On that thread, they were asking if they could submit ACT + SAT IIs without SAT I (so slightly different but still leaving out some of the SAT testing) and Duke admissions told them it was fine.