I have my own weak hypothesis regarding what you mention but I don't have anything really to back it up. Lineage A could have been the compromised tech and lin

I have my own weak hypothesis regarding what you mention but I don't have anything really to back it up. Lineage A could have been the compromised tech and lineage B could have been an intentional engineered release that is more contagious but less lethal to improve morbidity from A and reduce or mitigate the fallout, not that anyone would ever admit doing this to the general public.