Feeding live is of no benefit to your Corn. When the mice get old enough to bite back, they could hurt him badly. Sticking to dead food is much smarter. If you don't have easy access to frozen or you plan to breed your own, then offering mice fresh-killed will get over the problem.
The basic key to feeding is - does the food item leave a lump in the snake after eating for 24 to 48 hours after eating? If one pinkie doesn't, then you could try two at the next feed.
Eating faster doesn't mean that he's hungry, just that he's grown larger and can swallow a pink more easily than he used to be able to when he was smaller.