It might be possible to have two separate auto insurance polices for two different people on one vehicle. Insurance guidelines differ though so you would have to check with different insurance companies to see if what you want is possible and allowable by their guidelines.
Typically this type of double insurance on a vehicle is not necessary and may go against many companies underwriting guidelines, since normally one policy would be able to cover all the drivers of the vehicle.
A situation that we can think where two car insurance policies might be placed on the same vehicle is if there is a co-signer on a car that wants insurance on it in case the primary driver does not keep their insurance on it as they should. This type of coverage is hard to buy separate from all the liability coverage that is required on a policy. Furthermore, a co-signer can request to be listed as an additional insured on a policy. They are then notified of policy status, just as a lien holder is notified.
Each person in this type of scenario would have insurable interest in the vehicle. If the drivers involved did not have insurable interest in the automobile, than it could be difficult for them to place coverage on it.
So while it might be possible for two people to insure the same vehicle through different companies it might be difficult to find insurance carriers that would permit this.