It looks like you're using the Cert-manager ACME client for k8s. Unfortunately I'm not familiar with k8s or cert-manager and can't suggest the best way to add another name or to debug the repeated duplicate certificate issuance.
I recommend you follow cert-manager's troubleshooting documentation. There's also a Slack channel where you might be able to find more immediate cert-manager specific help.
As a note in case you're unaware, the cert-manager client has lots of problems related to hitting rate limits and we are in the process of blocking old versions. You should also confirm you're using the latest version.