I find that very hard to believe. My Cali King gets two large adult mice every ten to fourteen days and sometimes it takes her a good while to get them down. Plus if your Cali was eating two large rats every week, it would be doing nothing but digesting all the time.
The only Kings that would be capable of taking two large rats a week would be either an Eastern King or a Florida King and eve at that it would be a struggle with with a real danger of regurgitation.
If this story is true and you were feeding your King two adult rats a week, could there have been a chance you had mistaken your Cali for an Eastern?