Plugin is inserting meta data twice

WordPress SEO Plugin Version: 1.4.7

The plugin is inserting this block twice in the head tag:

<!-- This site is optimized with the Yoast WordPress SEO plugin v1.4.7 - http://yoast.com/wordpress/seo/ -->
<!-- Admin only notice: this page doesn't show a meta description because it doesn't have one, either write it for this page specifically or go into the SEO -> Titles menu and set up a template. -->
...various meta tags, mostly Facebook and Twitter open graph stuff
<!-- / Yoast WordPress SEO plugin. -->

You can see it happening here: http://tinyfarmstead.com/8-yards-of-compost-spread/

http://wordpress.org/extend/plugins/wordpress-seo/