One kitchen outlet is using 2 breakers slots in the panel

A tie bar physically connects the two breakers together • Locations 17, 18, 19, and 20 are empty slots and can be used for additional branch circuits

What he said is correct That is 2 circuits that take up one breaker slot Each circuit requires its own neutral Something you need to look

two breakers in one slot A tandem breaker fits two individual breakers into the size of one That allows you to add new breakers when your breaker box doesn't have any new slots

two slot Flip both of them upside down and compare the slots on them where they slap into the busbar I bet the slot is much larger on the regular