<p>I don’t think they can know if you take that test if you don’t send the score or list it on your common application. At least, that’s with the ACT. I’m not sure but I don’t think there’s much of a way around it on the SAT.</p>
<p>However, I’m pretty sure that Duke superscores. In my case, my highest ACT was a 31. The last time I took it, I got a 30 and dropped 8 points in a subject. However, one or two of my scores were my highest ever so I sent in that test. I’ve heard (not positive) that they only see your best scores. So even if you bomb every portion, send it because you might just get that 35 in math this time and bump up your chances!</p>