Many insurance companies allow for multiple primary drivers on a single policy, as long as all of the drivers live at the same address. When multiple drivers are listed as primary, they are all considered to be equally responsible for the car and the insurance policy. This can be beneficial in cases where there are multiple drivers who use the car frequently, or where one driver may not have a perfect driving record.
Keep in mind that the insurance company considers various factors while determining the premium, such as the driving history and risk profile of each driver. Adding someone with a less favorable driving record as a primary driver may result in a higher insurance premium.