I was going to do a rant about this here, but turns out I already did so nine years ago with regards to a controversy I've mostly forgotten, and since almost none of y'all were reading this site back then I'll just reproduce the key grafs:
[W]hy have one valedictorian in the first place? When I was in high school, we had one valedictorian from a class of 600, and it was nuts. Lots of us tried every angle we could to raise our averages -- some had their Science Fair work counted as an independent study, AP-level class; I had my co-teaching of a 10th grade Telecommunications class so credited, etc.
We all ended up within decimal points of each other. We all ended up at good schools -- our year, it was MIT, Brown, Amherst, Wash U and Penn for the top kids. And none of it was worth the resentment, bitterness or competition. ...
Just take the top 10-20 students, honor them all, and select the best speaker from among them for graduation. Life's too short for this bullshit.