doubling the featured image lengths

I am occassionally getting the link part of my featured image doubled up.

For example, the with the “image” class is empty, with a second with no class immediately after it containing the featured image.

I am using the custom excerpt-length feature, I believe this is happening when I have a manually-specified excerpt, but not when it uses the automatically generated one.

Example:
http://learn.stocktrak.com/

the “Word of the Day” piece. Refresh the page a few times, when there is a featured image of graphs over a map (on posts where I haven’t manually entered an excerpt), it looks normal, but for other featured images (on posts I’ve specified the excerpt), I get an extra empty link above the with the image class.

https://wordpress.org/plugins/display-posts-shortcode/