if you are getting errors trying to import / Export, that has nothing to do with power store.
if the power stores are both on the same domain, using the same localhost name for the mysql server will connect to the same mysql server.
you would nee to have 2 separate databases on that server.
when installing the store on the second site, you should not copy the files from the first site.
you should run the power store install script on the second site to create a unique installer and make sure to tell it to use a different database.