The Facebook graph debugger complained that there were multiple og:url values. I determine it to be a conflict between this plug and Facebook for WordPress.
The main issue I was trying to solve was adding photos for posts on FB. I use NextGEN for the primary photo and gallery at the bottom of the post, and FB was not recognizing the photos.
I was able to comment out some lines in the module to eliminate the duplicate og tags but now when posting on FB there are 28 thumbnails to choose from... e.g. http://blog.octanenation.com/news/aston-martin-chooses-2012-salon-prive-to-display-exclusive-models/
I'm new to WP and commenting out lines in the plugin doesn't seem too robust, and it's still not working as expected. Any insight would be greatly appreciated!