If you are going to feed p/k, and insist on feeding 2 rodents, offer them one after the other. Snakes in the wild are oppurtunistic predators, and will eat more than one rodent if they come across a burrow with multiple prey items contained.

As far as freezing and thawing rats...good luck with getting him to take it if you currently feed live. Sometimes its difficult to make the switch.

To thaw a rodent, place the rodent in a watertight bag and place in warm water for 45mins to 1 hour. After that, replace the water with hot water and get the rodent up to temperature (90+ degrees if you can). Offer the DRY rodent immediately.

Now for the advice you probably don't want to hear, but I'll give it anyway. If you're snake is big enough for 2 adult mice, its time to switch to rats. This is easy if you have a good eater. Simply select a small rat that is just about equal to your snake's max point of girth. You can place the rat in mouse bedding for a couple of hours to scent up the rat, and make it more familiar to the snake. As soon as the snake hits it, it tastes like a rat, and hopefully it will then identify the rat taste/smell as food, and a successful switch will be made.

Rats are more nutritious than mice, they have much more lean meat, bone mass, etc. than mice. Mice really are just a lot of skin, fur, and thin bones. Small rats = a plump healthy ball python.