The Design Manager can be used to change the design of an existing SharePoint page to a different 2007 design. The properties in this section apply to this use.
The Design Manager can be used to change the design of an existing SharePoint page to a different 2007 design. This option, which is enabled by default, allows you to copy the master pages from the template page to the source page. If you do not want to copy the master pages from the template page, leave this checkbox blank.
This option allows you to overwrite the existing master pages on the source site with the master pages from the template site if they have the same name. If you do not want to overwrite the original master pages, leave this checkbox blank.