Why does HTTPS show the website of a different domain?
When visiting a domain using HTTPS, Apache serves the top matching VirtualHost with the matching IP address from the Apache configuration file. If there is no existing VirtualHost for the requested domain, the Apache service will instead return the first one in the configuration for that IP address. An HTTPS VirtualHost is not created for a domain until it has an SSL certificate installed.
The first time you install an SSL on the shared VirtualHost IP for the server, that domain becomes the default SSL. The default SSL feature is designed to allow control over how the Apache Web service handles these requests.
After multiple certificates have been installed, the setting to select which VirtualHost you want as the default will appear in the WHM interface in Manage SSL Hosts. This is represented by the Make Primary link next to all other certificates on the shared VirtualHost IP.
For additional information regarding this feature and its interface, see the following documentation: