so as it turns out, "kazuto" is a given name with exactly the same kanji. this is the only time 一人 is pronounced this way. it's pronounced "hitori" every other time
so naturally "kazuto" is the pronunciation duolingo went with
japanese is a pretty good language. duolingo is a pretty good language learning program
@typhlosion@awoo.space It can sometimes be いちにん but it's uncommon iirc