It might be revealed as one of those earths, which would be awesome. We just wanted to “catalog” the DC universes that appear in other media (Nolan films, Young Justice, Arrow, Superfriends, etc). We stuck with 1-52 because (with the exception of Earth-0 or Prime Earth) those numbers are a little arbitrary. There have been three different versions of Earth Two and in a multiverse they still coexist, but their numbering isn’t important. So we are treating this like a different grouping in the DC multiverse and are repeating the numbering 1-52.