Morning Eater, Evening Eater

We've started noticing, Sumo prefers to eat his main meal of the day first thing in the AM (after pee/poop time).

Chibi on the other hand, usually waits until the evenings (after 8 PM) to have her main meal of the day.

Another random question of the day, why is it that Chibi will pee/poop during 1 trip outside. Sumo, will pee, come back in the house for about 5 minutes, then want to go back outside to poop. Would definitely save some time if he would do both at the same time. We've tried to keep him outside until he poops, but when we try that...he sits on the ground and just looks up at us like we're nuts (e.g. "Hello! I'm done!!!")