Ontario Highway Traffic Act

I was driving my car the other day, it was at night time I was going downhill on a 60 zone, I let my car go and I got up to a speed of 120. I got pulled over and the police charged me with act 172 and 128. He impounded my car and suspended my license. What I don't get is how come I got charged with 2 acts, shouldn't the officer choose one of them ...