Is it appropriate for someone to have 2 primary care Drs?

Ok this person was seeing one dr who wanted them to see a specialist for a specific issue. Instead they switched primary care dr as they not only wanted a second opinion but thought this other dr would be provide better medical care. Now the second dr will not prescribe meds without seeing them again that the first had previously had them on. So now they want to go back to the first dr to get the prescription fill but still go to the second dr as their reg primary care. I told them that is not ethical but wonder if other issues would also be involved. Their health insurance allows them to pick dr's without referrals needed. Just wonder what other issues or legalities could be involved?