Using two templates on same site

Apologies if this is basic but how would I use two templates on a site yet have hot install to include the data?

Install one hot start and other just template. If you use our templates best if you use both that are sparky based

Thanks. But again what about the sample data that comes with the templates; are they installed automatically when you install the second template on its own?

Sample data will not be installed if you don't install template with HotStart method.
You will have much more work to be done if you are installing template(s) without HotStart.
Please read this: www.hotjoomlatemplates.com/blog/joomla-i...-on-existing-website