Update: Gary Illyes from Google said this story is wrong:

Let me first start off with the title may sound more scary than it is, but I tried hard to come up with a short title for this post and I failed (traveling this week and I am tired). In short, with the new evergreen GoogleBot able to do more, some ad networks and other embeds GoogleBot can now render may render meta data, titles, canonicals, etc into your body content.

Google is aware of this and I guess is dealing with it some how.

Ryan Jones mentioned it on Twitter:

Both Martin Splitt and Gary Illyes from Google responded:

So it looks like Google is onto it – and I don’t know if this is actually causing problems for Google search or not but hey, it is interesting.

Forum discussion at Twitter.