User blog comment:Wales8450/Supergirl and Batwoman Episodes/@comment-28109177-20200120201623

It's the Crisis after-effect! There are doppelgangers lost on Earth-Prime roaming among their doubles because their Earth were destroyed, when the Earths merge. All of those Brainiac 5's were from different Earths that were destroyed, The second Beth Kane was Beth from another Earth in which she never became Alice.