Installing two versions of Drupal 8 On one Domain

I am running a news site on Drupal 8. Now I am planning to make a business directory. For that I chose the URL as As the nature and proposed design of a business directory is too different from a news site, I thought it would be lot easier, cheaper and less time conmsuming to install a new version of Drupal 8 with a directory theme ready to use instead of a making a directory pages as a part of the main Drupal 9 site.  I know it is a bad practise. But I just wanted to confirm whether it is too bad, OK or so so idea to run two separate instances of Drupal 8 on a single domain?

Thanks and hopefully, I can get expert opinion form few of you.

Thanks and regards

Drupal version: