Double Title

It is connected the usage of the filter hook regarding the title (e.g. wp_title, the_title, the_title_rss).
One solution could be to add a little condition to the functions.php file of the theme. You will probably find the line:

add_filter( 'wp_title', 'risen_title', 10, 3 );

in that file. It means that the function risen_title will modify the title. The documentation of this fundtion (in file \includes\customizations.php) says: Apply custom <title> format for homepage or subpage as specified in Theme Options. In my opinion this means the function is meant to customize only certain titles and not the ones of the news feeds.
That is why I would suggest to add a little condition to the risen_title function:

function risen_title( $title, $sep, $seplocation ) {
		if (FALSE === is_feed()) {

			...

			return $new_title;
		} else {
			return $title;
		}
	}

This means if the request is one for a feed then this function will simply return the original title value. Otherwise it will do what it is supposed to do.