More than one domain with dietpi_letsencrypt

Can I request for a certificate valid for 2 domains with dietpi_letsencrypt like I can with the regular Let’s enctypt certbot utility?

If I can, in case I have already requested one (and thus my nginx default server configuration is already set for one), what will happen to my configuration? will it be overwritten? will a new server entry be added to the “default” file?

Tarrasque
You can easily extend the list of domains for an existing certificate with the certbot binary: https://certbot.eff.org/docs/using.html#re-creating-and-updating-existing-certificates

We have an open request to allow adding multiple and wildcard domains, but this is not a short-term task on my plan, so might take a while if not someone else finds some time to contribute.
But as dietpi-letsencrypt uses the regular certbot binary, one can adjust everything as above.