Contribution or Dual Insurance
Contribution or dual insurance as it is sometimes called arises when more than one insurer is insuring the same risk. The principle of indemnity does not allow the insured to profit from such a situation. The insured is entitled only to receive the amount of his or her loss. They are not entitled to claim the full amount under both policies.
If a customer has two policies they can claim on, they can claim on either. It is up to the insurers to determine who pays what and in what ratio.