I have multiple WordPress blogs on the same host all under /public_html.
I'm running them on a single database. Once I made the first one with all the themes and plugins I'm interested in, I just copy the whole /public_html/wp directory (my original install) to a new location (typically addon domain) and I edit the wp-config.php $table_prefix field and get s new install. I next have to activate all the same plugins (entering the same ids etc and setting up) and design my look and feel with the same widgets, theme etc.
This takes quite a while (I have many plugins and widgets).
Is there any fast way of duplicating the whole site (including the ids in various plugins, the widgets, the selected theme etc) quickly and then I could make the minor changes like the name of the new blog, affiliate links and so on?