The 'Version Number' field, where enabled, allows you to assign your own versioning to templates. When template changes are applied to the database the version number will be written into the XML.
Warning -The 'Version Number' field applies to the current template only and multiple templates with the same name and different version numbers cannot be used in the Wizard. This prevents users accidentally using out-of-date templates.
If you want to keep previous versions of templates for historical or review purposes, export the template definition and save it to a secure location on your network. If re-imported later the current template will be overwritten.