Excerpt calls two thumbnails

This site (http://wdiet.net) uses several pages and posts to draw from for its Index page content. The “Featured Story” section on the bottom should draw from the thumbnail of the first post of category 46, which it does. However, now that an image has been added to the article above it (Welcome from Kalalea,) it inserts the thumbnail from that post as well. Any idea why this is happening?

Thanks!