WordPress installation in Root and second installation in directory

I used to install WordPress in directory on my ftp for instance ../wp
There i could make more installations withou problems. So i had ../wp ../wp2 etc.

Now i installed it in the Root of my fpt but then the permalink rewrite will disallow the second installation in directory.
It will come up with a 404 error.

My Solution is simple i made a subdomain ( for example wp.mydomain.com) if hosting partner will allow you to do so in Plesk or control panel. Then it will work perfect. Because it is an other folder and not /http/yourdir anymore. Now permalink and .htacces will not send 404 error