"Well, for one, the buzzers go to individual apartments, so no chance of a mix up, as long as you hit the right buzzer. As for how we tell each other apart, we got used to it. Nobody calls me 'Ed' anymore, for example. I'm just 'Edward' now. I'm also known as the cranky one, which is unfair. But eh. These two you see in this building, one's shorter and a homunculus, the other is taller and human. He also has two flesh arms, instead of one automail." Edward holds up his own hand for example.