This is 100% how a lot of medical offices and/or insurance operates. For some practices that perform complicated procedures bills will get sent with a "catch-all" sort of approach of all possible scenarios that could have happened and you have to go back and tell them what treatment you actually got.
Insurance companies will also just initially deny claims in the hopes that people won't spend the time to debate it. My wife had to get back injections for a bulged disk and insurance initially denied the claim on the basis that "it was not inhibiting her daily function". The original request from the doctor included the wording of "this is medically necessary because the pain is inhibiting her daily function" because he knew that was their criteria. Insurance still just rejected it because it is easier for them to do that and only accept the claims people fight for. Luckily in this case the doctors office was on our side and called the insurance company to get it approved. The doctor said that this kind of shit happened all the time.