It does not seem very plausible that professional astronomers have twice made this rookie mistake and no-one has noticed yet. Furthermore, if they were just doing what amounts to drawing circles and lines on a map of galaxies, they could have discovered thousands by now!
Well, yes, but my point is that, if these astronomers are finding circles and other structures without doing basic checks such as distance, they could find thousands right now, using nothing more than a chart of the known galaxies - and even bigger ones than they are reporting here. Thus, it is not plausible that they are omitting these basic checks.