Two in one

Sarah and Steve glowed briefly, and when the glow dimmed, Karyn looked open-eyed. Where Sarah and Steve had been was a strange creature. It had four legs, four arms and two heads - the heads of Sarah and Steve! Both heads went into one torso, which still had Sarah's breasts. Four arms protruded, two of them feminine with nail varnish. Two of the legs were wearing tights and high heels, the other jeans and trainers. The creature moved off, seemingly oblivious to the change. Karyn looked at the box in horror, and she dropped it. As the switch fell, it flipped over, and landed on the button, which depressed. Unfortunately, the box was aimed at...