Looks like there is a bug with Google's implementation of AMP. Google is now showing AMP icons and content in the core desktop results. They recently launched AMP in the core mobile results but AMP should NOT show in the desktop results.
Ashley posted on Twitter that they are now showing up on desktop. And yes, I was able to replicate it. Here is a screen shot of this site showing its AMP pages in the core Google desktop results and yes, when I click on them, it goes to my AMP URLs.
Malte Ubl said on Twitter that "the Search team is looking at it." I guess this is a bug and he thanked Ashley for the report.
Here is AMP on desktop for a search on [amp]:
Forum discussion at Twitter.
Update: Now when you click on the AMP desktop results, it does nothing. Major traffic implications on this bug.
Update 2: After about 60 minutes or so, it seems Google is rolling out a fix.