install a normal wordpress like it was to install only one
in this case in /var/www/vhosts/domain.com
Website 1:
Domain name: domain.com
Physical folder: /var/www/vhosts/domain.com
URL: https://domain.com/
CMS: WordPress One (with database one)
now /var/www/vhosts/domain.com has all wordpress files and folders
in this directory /var/www/vhosts/domain.com create a new folder called test
now install a new wordpress in /var/www/vhosts/domain.com/test
Website 2:
Domain name: domain.com
Physical folder: /var/www/vhosts/domain.com/test
URL: https://domain.com/test
CMS: WordPress Two (with database two)
and this is how you get two wordpress sites with two different databases in the same domain. basically you create a folder inside that has another wordpress , the main wordpress never goes there because doesnt know that exists. and can be access by directly writting the url with the folder name. this is good for developing a second version of the website, or to have two websites in one domain also.