DKIM record at {selector} repeats a tag
URGENTWhat it means
The tag the offending value appears more than once at selector1, which makes the record invalid. Verifiers are entitled to discard it entirely.
How to fix it
Keep one instance of the offending value and remove the duplicate.
Check your own domain
This page describes the condition. To find out whether your domain has it, run the DKIM test or the full checkup, which examines every record at once.
Understand it properly
This page covers one condition. For the whole picture, What is DKIM, selectors and key strength, or start at the Health Library.
Where this comes from
We judge this against RFC 6376 section 3.2. Every finding on this site cites the specification behind it so you can check the work rather than take our word for it.
Other DKIM conditions
DKIM_DUPLICATE_TAG
Every fix on this site is yours to implement. If you would rather someone did it, I take this work directly.