Can I clone WP to another directory on the same server?

I would recommend to clone it on a subdomain. Something like “testing.myfriendswp.com”.
I have tried this approach and it works fine.
If you have a cpanel, you will see an option to create a subdomain in it. create a subdomain and point it to a folder inside public_html.
So, for example, your subdomain “testing.myfriendswp.com” will be pointed to a directory “public_html/testing”.
Once you have the subdomain created:

1. copy the WP files from the main domain to subdomain
2. create a new database and import tables from the main DB to it.
3. set appropriate DB credentials in wp-config.php file
4. change the domain name in the wp-options table in the new DB.
5. boot up WP on the subdomain and refresh the permalink settings.
6. Run a search replace script on DB to replace main domain to
   the subdomain.

For extra security, add a robots.txt file on your subdomain to prevent the instance from being crawled by Search Engine Robots.

Thanks