Duplicate author links with Co-Authors Plus and WP 3.9

Hello,

Just upgraded to WP 3.9 and the latest versions of everything else, and Co-Authors Plus is displaying duplicate listings of authors on posts. It worked fine before. I have commented out this line in my child theme’s functions file, which yields the first author only:

$postinfo_meta .= et_get_the_author_posts_link();

and added this:
if ( function_exists( ‘coauthors_posts_links’ ) ) {
$postinfo_meta .= coauthors_posts_links();
} else {
$postinfo_meta .= et_get_the_author_posts_link();
}

Result displays as:
Author 1 and Author 2by Author 1 and Author 2

How do I remove the duplicate? The same behavior occurs when a post has only one author (Author 1by Author 1).

Thanks!

https://wordpress.org/plugins/co-authors-plus/