Question regarding dental bill…

Hi everyone! I received a bill/insurance claim from my dentist with a date of service I was never there, and it lists filling work on teeth I’ve never had treated. When I called the office, they seemed unsure and said it might be for “future work,” but I was never told I needed anything done on those teeth and nothing like that was discussed with me. Has anyone dealt with this before, and is it normal for a dental office to submit claims for future procedures, or does this sound like a billing error? What’s the best way to handle this with both the office and my insurance? Thank you in advance!