one theme two different pages?

You can use the same theme on any installations of WordPress.

Also, if the domain you’re working with is the Primary domain, you can use the multi site feature by creating a wildcard subdomain like *.yourdomain.com, or you can force WordPress to use subfolders instead.

See: http://journalxtra.com/2010/07/how-to-force-multi-site-to-use-subdirectories/