Characteristic &1 is used more than once

What causes this issue?

Characteristic &V1&, referenced as number &V3& in certificate profile
&V2&, is used more than once.

System Response

The characteristic cannot be uniquely assigned. As a result, processing
for this characteristic cannot be continued.

How to fix this error?

Do not print this characteristic on the certificate or make sure the
characteristic is used explicitly.

Error message extract from SAP system. Copyright SAP SE.