Hi,
we also create some "demo" copies for testing purposes and to create some playground for users.
You have to create a "demo" copy on the same server as the "live" installation.
Copy whole EPESI directory, create a new database (copy the "live" database), change the new config.php to use the new database.
In such situation you will get two separate installations with the same data, same modules and same license key. (eCommerce needs some more adjustments as quickcart settings are stored somewhere else). However we don't allow users to reuse license key, but it's the only situation where you're allowed and it's recommended to create such "demo" installation. But remember to create them on the same server.
Regards,
Adam