The responses are unclear. Both 99215 and 99396 are E/M codes. The question is which one gets the modifier 25?
If the patient presents for their comprehensive / routine visit and something unexpected or peripherally related to the reason for the visit comes up that must also be addressed, then where does the modifier go? The chief complaint is addressed in the 99215, the ancillary matter is 99396:Which gets the modifier?
Look at the CPT® book, at the start of the section on preventive medicine services and you will see that the modifier goes on the problem oriented visit. The CPT® book often answers these types of questions if you read the editorial comments.
I would strongly recommend that you do not report 99396 and 99215 together. There is to much overlap in the services. The history and exam for the 99396 and 99215 will be similar. You will not meet the MDM requirements for 99215. This is an invitation for denial and audit.