I'm using plesk, how do I get a CSR for 2 domains at the same time?
If you want to generate a Certificate Signing Request (CSR) for your domains, then it depends on the type of SSL certificate that you will use. If each domain will have a separate SSL certificate, then you will need to generate one CSR for each domain.
If you are using the "Let's Encrypt" Plesk extension, then you should read the documentation on how to use it.