What this doctor is doing is illegal and needs to be reported as soon as possible to your insurance carrier. They likely will not refund whatever money has been paid, but will withhold future payments until the amount in question has been covered. You should definitely not be required to pay a double co-pay in any instance. I worked as a medical assistant then as accounts receivable for a succession of doctors. A succession because as soon as I realized they were insurance cheats I would find another job. There is no way I could give false testimony before an insurance inquiry. And I once made an appointment for a check up with an ophthalmologist who tried to charge me for a prescription for new glasses when that's not what I needed (in addition to the office visit). I said no, and went home and called the insurance company which told me to forward any bills I received from that doc (never received one).