A Manual PPN with reason code & already exists

What causes this issue?

A manual PPN with the same key information already exsists. This check
is done against table OIU_RV_VPPNM

System Response

This is a system error, you may not continue

How to fix this error?

Either change the PPA reason code or leave it blank

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.