Coinsurer data already used by coinsurance key &1

What causes this issue?

The specification for the coinsurer are already being used in the
coinsurance key &V1&. Therefore, the coinsurance shares can not be
uniquely identified.

System Response

The specifications for the coinsurance key are inconsistent.,,,,

How to fix this error?

Check the specifications for the cost contracts.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.