Double Seams

On a recent trip to Magnuson Park in Seattle, I took a few pictures of a young Cardinal Meadowhawk.  When I looked at the photos later it seemed like I was seeing double.  Here's an example of what I mean:

Notice the double images along the abdomen, specifically at the seams between the segments.  I wondered if I had jiggled the camera somehow, or had a smudge on the lens, but the double images were in all the photos.

I had never noticed before that the seams are doubled, but it turns out that it's easier to see the effect in young individuals, when the abdomen is light colored.  The double seams are still present in a mature adult, but they're not as prominent, as can be seen in the following photo:

I decided to check other meadowhawks, and have found that Striped Meadowhawks also have these unusual double seams.  Here's an example:

I haven't found this effect in other meadowhawks yet, like the Autumn Meadowhawk in the next photo.  I'll keep checking, though.