Yup! Crazy Chaos side affects. :D Sorta, they keep the negative chaos energy from controlling Sonic apart. Just like how in SA1 perfect chaos only used the negative energy of the emeralds and then sonic was able to use the positive energy. And from seperating the dark half, it split Sonic into two different beings. Sonic and Chaos. Sonic being the positive energy and Chaos being the negative energy. But they still share the same body, just like how the chaos emeralds hold both negative and positive energy.
Yup! Crazy Chaos side affects. :D Sorta, they keep the negative chaos energy from controlling Sonic