Only the top two pistons Move when the brakes are applied

The front brake calipers only the top pistons are pushing out the brake lines have been replaced. The front left brake calipers replaced. Still the same result only the top two pistons move when the brakes are applied. They were bled properly I started from the right rear went to the left rear front right front left. I have plenty of brake pedal, no sponginess, doesn't stick. Just the pistons won't move together on either side and as I said the front left driver side is brand new.