Given Miami's reputation as a top notch educational institution and their extremely high entrance requirements for football players, having a majority be brainiacs who graduated in 3.5 years makes sense.
On a serious note, graduating HS with an AA degree? That means that you finished your high school requirements (including the usual college prep curriculum) and two years of college courses in four years. That's six years of material, much of which includes a series of prerequisites, in 4 years. I've heard of people earning a semester's worth of college credit, but never heard of earning a 2 year degree while still in high school. The only way I see that happening is if the kid takes a heavy summer course load and has some courses count for both high school and college credit.
I'll ask my daughter (no pics). She graduated HS in '17 with a 4.0 and took all the advanced courses (AP, honors, etc.). She knows all the high performers in a HS with 2000 students, she'd know if that was happening at her school.