I would bill them on the same claim, but showing the dxs for the different body parts on the appropriate lines. I would also use the appropriate modifier to indicate that the services are separate. With that being said, they still will most likely be denied. You can appeal them with notes and an explanation, but it may not help. Another option is to contact the insurance ahead of time and ask if there is anyway to treat the patient for both issues on the same date. They may authorize it that way, avoiding the denial.