Installation &1 scheduled billing date &2: inconsistent billing orders

What causes this issue?

The system has determined an inconsistency. More than two billing
orders exist for installation &v1& with scheduled billing date &v2&.

System Response

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

How to fix this error?

INCLUDE ISU_SAP OBJECT DOKU ID TX

Error message extract from SAP system. Copyright SAP SE.