Both of them are correct, but they do not mean exactly the same thing. "You did once" means "You did before" - you did something for some period of time before now. It may have been multiple times, just before now. "Did you go to college." "I did once, but that was a long time ago." "You did it once" = You did it one time "Have you gone white water rafting?" "I did it once, but it was too much for me. I won't go a second time."

In context, both are fine.