TemplateM8 is an contao modul to add multiple templates for content elements.
Just create a template in the templates folder with the m8_ prefix and your custom suffix _myTpl.
m8_ce_text_BackgroundImage.html5
m8_ce_image_myOwn.html5
templatem8 allows you to give the templates "meaningful names" like "with Background Image" instead of "m8_ce_text_BackgroundImage".
All you have to do is to create a new language entry in your langconfig or module.
$GLOBALS['TL_LANG']['templateMate']['m8_ce_text_BackgroundImage'] = 'with Background Image';