Example: A medical office that has more than one doctor or practitioner. I have seen this on multiple occasions where each doctor is using the exact same address.

How would you avoid duplicate listings? What best practices would you recommend?

My thought is to ensure the NAP is unique.
Practioner #1:
Business Name: Dr. John Smith
Address: 555 Doctor Ave. Ste 500-A, Chicago, IL, 60001
Phone: 666-666-6666

Practioner #2:
Business Name: Dr. Anne Johnson
Address: 555 Doctor Ave. Ste 500-B, Chicago, IL, 60001
Phone: 777-777-7777