Christa,
I went from free feeding to twice a day about a year ago. Like yours, mine would gobble up their food and still act starved. But, without my noticing much, they gradually did exactly as you describe - and leave food in their bowls. After about 20 minutes, I return any leftovers to the large food container and they wait until the next feeding.

Now, I am thinking that when the measured feeding began - they were worried they would not get more food and so just ate more than they needed - my theory I know that food sure lasts much longer so they must have been overeating with the freefeeding.

Sounds like what yourd may be thinking - and now eat less because they know they get more later in the day