I'm trying to install multiple Gantry themes on a wordpress site. I installed the first, renamed the folder, changed the theme name in the style.css file and changes the name value in the templateDetails.xml file. Then I installed the second instance and went through the same renaming steps. But, when I try to configure each theme in the gantry admin area, a single change is reflected in both templates. I checked the database tables and it is creating exclusive tables for each theme name, so I don't know what the problem is.
Try like this, when you install the first copy the theme to desktop, change the theme name in the style.css and templateDetails.xml and zip the whole theme and then use the installer to install this and see if it will work then.