I came across this unusual Google AdWords ad, and it definitely caught my eye, since it had two identical lines in a row – the sitelinks in one line, and the duplicated sitelinks, without the links, in the description line.

It could be just how the company decided to do their ad copy, rather than a test Google was running.  It definitely caught my eye in the search results for a search I wouldn’t have likely noticed the ad otherwise (it was not a test search).  But it was pretty unusual that it lined up perfectly.

If it is a Google test, perhaps they are simply reiterating the most popular site links for an ad in the description and they just happened to match in this particular case.

Here is another example, with some annotations in the middle.

If it isn’t a test, it might be worth running your own tests with matching sitelinks and descriptions and see how the CTR is compared to non-matching.

Added: It could be duplicated callout extensions instead of description.