Tax Number for tax category: &1 already exists

What causes this issue?

With this object you can only add new tax numbers with new tax
categories. You can't change already existing entries.

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?

Delete these records from the template or change your mapping.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.