Conjecture: Well, they are a newer model and HK-47 is "obslete." HK-47 recognizes them as himself because they are made from his schematics and can't kill them because of his self preservation package. I believe that because the HK-50s are a newer model, they don't recognize HK-47 as one of them because they probably have newer features HK-47 doesn't have, therefore they are capable of attacking HK-47.

Condesending Query: live draw hongkong Where would the fun be without hostiles to sluaghter?