Indeed, looking at the page source, there are two links to the same image. They seem to be created by either the theme or Woocommerce. Not sure why though. It might change depending on theme or Woocommerce product gallery settings but I’m not an expert there.
You could disable the Autogallery opion on Settings > Media. Or set it to “WordPress galleries only”. This will work around the problem but obviously, the user will not be able to navigate to the next image without closing first.
I’ll submit exclusion of duplicate images as a feature request !