Anyone noticed an extra Google AdSense ad at the bottom of Geekzone pages on Lumia Denim devices?

On a Denim device it shows a mobile-version of an AdSense ad floating at the bottom. On Android and Lumia Cyan devices it shows nothing.

I checked the code and we don't send out mobile ads. I'm thinking some strange browser behaviour causing Google DFP/AdSense to deliver two ads - the normal version and a ghost mobile version?

Anyone who could debug this?