I am seriously doubting that, given CA's general reputation in her neighborhood (mentioned by the neighbor that gave the interview regarding Kio) that either CA trusted anyone in her neighborhood enough to give them a set, or that anyone they knew close by would want one.
JB can use a theory of other sets of keys to create doubt, but I don't think it will come under the definition of "reasonable" at this point in the game. CA and GA themselves have lied or changed their stories so much that I doubt even a receipt for a duplicate key would convince anyone. Even SODDI defenses have to have enough credibility to stand up against other evidence against the defendant (in this case overhwelming). The explanation of another key MIGHT have flown if they could have proven the existence of the imaginanny, but that whole story was hanging by a thread from its inception, despite the feeble and amateurish attempts of CA and GA to "corroborate" it later.
If you want to have a SODDI defense that even stands a chance in court, in addition to creating reasonable doubt with the theory itself (emphasis on reasonable), it always helps to sell it better to a jury if the defendant does not come across as a spoiled, remorseless, narcissistic thief who has an undisputed reputation as a pathological liar by her friends (has been accused of being a sociopath by other family members), and the defendant's parents do not, for the most part, behave in public as angry, entitled liars as well. I don't think a class A defense attorney could do much with this case, much less one that is up to his unqualified knees in a concomitant review of his own questionable ethics.
