That’s the same thing. In order for that tracking method to work, this uniquely named pixel has to be loaded while visiting multiple sites. So it ends up being multiple domains referencing the same image from some tracker resource.
I suspect you'll find this is _way_ more common than you expect.
(Also, if you thing Goog aren't doing this with their font CDN or various javascript library coaches, even (or especially) for sites without Google Analytics... I've got a bridge to sell you...)