Every once in a while I'll have a snake give up on a prey item. This usually follows them dragging it through the water bowl and/or not being able to find a good starting point in the swallowing process(some snakes won't mess with a prey item after a few failed attempts at finding the head through trial and error). It's possible you're getting defensive strikes from balls off feed, instincts are taking over and they're coiling the prey only later realizing they're not in the mood.. Are they males perchance? That might explain their high activity and unwillingness to feed this time of year. I'd offer again next feeding day and try to give them more privacy(leave room, cut off lights) for a good hour or two to make sure it's not just a disturbance issue then go from there.