Besides the redshift difference, astronomers measured how much the ultraviolet light from Markarian 205 dimmed as it passed through interstellar gas in NGC 4319. The numbers they obtained from this data suggest that Mrk 205 is 1 BILLION light years away as opposed to NGC 4319's 80 million light years distance.
Of course, as with any good science, the jury's still out until the evidence for the "non-connected" theory is complete.
Anyway, enjoy tonight's beautiful Hubble image!