Fair enough; but the article doesn't mention how close together they are. Judging from the diagram, they're separated by an angular distance roughly the same size as the larger structure; so about 3 billion LY.

If you've got two structures of size X, with a distance of X between them as well, that's relatively close.

That's as if Paris had a second Eiffel tower three blocks away.

Yeah, that makes sense if Paris is just 15 blocks across, and the Eiffel Tower is a couple of blocks wide, and there's nothing (observable) outside Paris.

And that doesn't even mean they are really close between them linearly.