I am usually against two characters per island, however, I would really love to have two on Dwilight. Dwilight is simply extremely diverse, culturally different and hence very appealing. I currently play in SA, I've tried the Lurias and have an appetite to try out especially Aurvandil and the Moot. However, I would want to be able to continue to play in SA too. With only one noble allowed this is impossible.
If you offer two nobles per island then make sure you offer it on the right islands. Cultural diversity of Dwilight and the size of the island makes Dwilight really the prime target for having two nobles. I really don't think many would place two of their characters in the same realm for those reasons. If you allow two nobles on Atamara, which, in my opinion, is the lamest island with all that old schools players, mute realms and dead beat religions that have no other purpose but to prevent your enemy from RTOing you, then I don't see why you wouldn't allow two nobles on a continent that is much more vibrant and much more interesting to explore.
I am well aware that there is no way dwilight will get a second noble slot, but I just wanted to say that I'd greatly support that. In fact, I think it would be much better to have all islands have a 1 noble per island rule, with dwilight being the exception where you could have two. wishful thinking i know.