I think that they may be either springlock victims or agony-although from what I do not know. Perhaps them being springlocked employees is true-after all, we are told that there were multiple simultaneous springlock suit failures, but...the shadow animatronics aren't physical beings. Perhaps the agony that came from their deaths reformed to create Shadow Freddy and Shadow Bonnie, or perhaps it was one of Afton's experiments. But this isn't about my theories. It's about yours. Go on, my children, and dazzle me!