It is never said why the NYC dupes were put there was it? Cause even when Max visits him in LA he doesn't mention the dupes and the dupes never mentioned who their protector was. My theory is that Langley didn't want to deal with Antar and his alien life anymore and just wanted to pursue a new life on Earth and abandoned them.
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It probably would've cost too much to have Langley in more episodes, The way I figured it is he just didn't want to deal with it, and of course he would have to do whatever they told him to do. And of course the New York 4 where the evil twins, except for their version of Tess, who was the opposite of the other Tess.
If the show had gone on, I'm sure they would've been brought up again.
Have written some of what I think takes place with them and travelling, though not quite completed, and have another one that is in the beginning, though all needs editing badly, can creative write, but no good editing. The only one alive from the NY group is Ava, as Tess killed them (this having her say she didnt know was crap, and have stated that and more in a review or thread or something re Tess).
Though in what I have written, Ava has not shown up, hope she does in the second one I have just started. Wanted her to be in the story but she just wasnt there.
As for the way they were raised, raised with the complete knowledge of all but think they more or less "raised" themselves, so to explain lack of or bad accents, they really were not apart of the human factor, so did there own thing ? and really did not care for anyone but themselves and even then more just self. Also dont think their protector, Langley, was there for much time, just enough to make sure they more or less survived.