Orientation usually peaks in the early afternoon. It's not unusual for the hives to be doing it at the same time. Robbing usually involves more frantic flying while orientation is a bit more leisurely. Also, I've noticed that when robbing is underway, there will be lots of bees probing for entrances on the sides and back of the hive. They will sometimes move from the side toward the main entrance in a rush, trying to sneak in. There will usually be fighting around the entrance too. Did you see any of those signs?