Installing C5 in correct folder/directory

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I am using Simple Scripts to install C5 on the server of my webhost (iPage). I designated it to be installed athttp://mydomain.com/c5. It installs at the root level (ie. root/c5/) and so all of my 6 different domain folders (which are each under the root level) can be edited by this one install (they are all unrelated websites). In other words I can go to mydomain.com/c5 or yourdomain.com/c5 and get the same exact landing page and c5 control panel. I've read where it is best to have one install per domain name. Any ideas?