It looks to me like those second hits are high, and thus should be ducked under but JC is getting hit. I have read somewhere in another thread that things like this happen because JC sways back and forth when he's in crouch, so depending on which way he's leaning at that moment he'll sometimes get hit by high attacks when duck blocking. Although, in actual play if they duck the first swing, then you're going to get punished before the second swing.