My speculation on what happened is: The first controller was in training and the second controller was their trainer. The trainee cleared you into the Class B but the trainer though that was a bad idea (perhaps there was traffic nearby they couldn't have kept you away from, or they wanted to teach you a lesson about calling too late, or they thought their trainee was too busy to provide VFR services, or they woke up on the wrong side of the bed that morning) and came on frequency to contradict the trainee's clearance.
When controllers are first hired, and any time they transfer facilities, they have to complete on-the-job training. This is because:
- Learning how to control simulated traffic in the schoolhouse is not good enough to let a new controller talk to actual planes with actual people in them making actual crazy requests they never had to deal with in the simulator.
- Airspace and procedures are different everywhere. Even if you were the best of the best at your last facility, you don't know all the nuances of the new facility.
- Different facilities have different controlling techniques and requirements. It's very possible for someone to transfer from a tower-only flight-school-heavy facility to a radar approach control working commercial traffic into a Class B or even to an enroute center.
That's why you'll sometimes hear a second voice come on frequency and tell you to disregard what the first controller just said. It won't be a supervisor, it'll be a certified controller who is conducting training.
