Yes it is possible to have multiple domains point to the same site or to a directory on your site.
The primary domain on your account will always be pointed directly to the public_html directory. As you assign additional domains to your account, you can assign them as either addon or parked domains.
An addon domain allows you to specify a directory inside of public_html which the domain will point to. A parked domain will point directly to public_html the same way your primary domain does. When assigning a domain as an addon domain, you are allowed to use the same directory as another addon domain. This will result in both addon domains pointing to the same folder and website content.
