[Plugin: Co-Authors Plus] Co-authors plus plugin posting twice – Bangkok Press Theme

This plugin is a great idea! Just having issues with the Bangkok press theme (http://themeforest.net/item/bangkok-press-responsive-news-editorial-theme/1613446)

When I replace the tags the authors names are appearing twice. I realise there is a solution for another theme but my code is a little different. currently my code looks like this

echo '<div class="single-thumbnail-author"> ' . __('by','gdl_front_end') . ' ' . get_the_author_link() . '</div>';

When i make the change here

echo '<div class="single-thumbnail-author"> ' . __('by','gdl_front_end') . ' ' . coauthor() . '</div>';

I then get the name displayed twice.

Thanks for your help

http://wordpress.org/extend/plugins/co-authors-plus/