To have two skins working with their own styles and templates, you must create a new template set and replacement set for your new skin, not making it work with the default templates and replacement set. If you make it that the default skin and your new skin uses the same template set, then both skins will look messed up, having the templates mixed with both skins. So leave the default skin with its default templates and replacement set, and have your new skin have its OWN template set and replacement set. If you had hacks or anything else on your default template set, you'll have to re-add the template changes again to the new skin. Hopefully that made sense. Cheers