AMC 10 for 8th graders?

I heard that if a middle school student gets 20 questions or higher on the AMC 8, then they can take the AMC 10. Is this true? I got 20 questions right, and I was wondering if I would be taking it. Also, are the questions from the AMC 10 that the middle school would take the same exact questions as the one the high schoolers took a while ago?