Dante Silverfire is absolutely right about the single character thing. Multiple characters per island results in many, many problems. Disposable characters, drones, zombies, etc. People will have their "main" take the positions, and then use their "alt" to do the boring scout tasks that no one in their right mind would want to do. Positions are given to the Duke's second character, because you know you can trust him. Realms A and B never go to war or have disagreements because all the key players in both realms are the same, just with different titles. The Marshal of the army of Realm A moves to attack because "my cousin in Realm B told me the attack arrives at sunset". Second characters are often ignored, and used as nothing more than faceless/mindless troop leaders who's only purpose is to provide more muscle for the army.
Yes, some people may play their characters as separate entities. And some may even play them as possibly working against each other. But I don't think anyone really feels that applies to the majority of dual-character families, especially when the characters play in the same realm.
Remember that islands change. The play experience on most islands changes dramatically over time. Give a different island an honest chance. Just because you hated Dwilight in 2009, the year after it opened, doesn't mean that you will hate it today, six years later. None of the realms from back then even exist anymore. Similarly, EC has undergone great changes in the past two or three years, as has BT. Well, OK, Atamara hasn't changed one damn bit until today, but there's always an exception.
