Can you install multiple SSL certificates on a single account?
You can install multiple SSL certificates for a single account, but this has limitations based on how Apache manages them. Only one SSL certificate can be installed per Apache virtual host so that each additional SSL installation would require a unique one.
When installing an SSL certificate, this generates an HTTPS virtual host inside the Apache service configuration file. This virtual host determines the certificate information used when a page request reaches your Apache webserver.
There are two options available when configuring additional domains inside the cPanel interface: Alias and Addon domains. When creating a new domain as an Alias, this is set inside the same virtual host and will share the same SSL certificate. If you choose to create the new domain as an Addon, this generates a subdomain with a unique virtual host. With this option, you can then install a separate SSL for the new virtual host.
For additional information regarding this, I'd suggest referring to the following article.