Not all payments could be added to the check repository

What causes this issue?

During the payment media run for checks, the system tries to add the
payments to the check repository. The document number is used as the
check number.
This was unsuccessful however for at least one payment - document
number &V1& - because there is already an entry with the same key.

System Response

The system continues trying to add payments to the check repository.
You have to maintain some of entries in the check repository if this is
the first execution of this payment media program for this ID.

How to fix this error?

Use transaction FKCHK to postprocess the entries in the check
repository.

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.