Secondary Insurance Ghost Entry?

Hi, I have been noticing some denials from Medicare despite everything looking good from our end. I then stumbled across a random number that no one in the office has entered in one of the fields of the EMR in the EDIT CURRENT PATIENT SECTION for several patients. I believe that this same number is automatically being generated for all NEW PATIENT charts in this exact location (GROUP NUMBER in SECONDARY INSURANCE) only, I’m not sure how though.

Has anyone else experienced this issue? What would be the recommended solution?