No two things ever happen at exactly the same instant in Olympia.
Someone always goes first.
Osswid's command begins before Candide's, since Osswid appears before Candid in the location list. Therefore, Osswid will enter the inn first. Order precedence between units in different provinces is undefined. If Osswid and Candide both leave for city B on the same day, we cannot predict who will get their first.