Board Thread:Arrow discussions/@comment-1783334-20170516181147/@comment-24152851-20170801140244

Because there's no point in him being an alternate Earth Adrian. Unlike Black Siren who was already an existing character, Vigilante and Prometheus were introduced together so they can't have one replacing the other. Why would he randomly start gunning people up instead of trying to get home? Also, how did he get to Earth-1 in the first place? Only the metas and technology over on the Flash allows dimension jumping.

The only way that Vigilante is an Adrian Chase doppelganger is the good twin/evil twin theory. Though at this point if they do a mythology nod to the comics, it's more likely that Vigilante's birth name was Adrian Chase before Simon Morrison committed identity fraud.