Christopher and Nicholas.
I'm not a huge fan of Nicholas, but I think they sound nice together. And then there was Ridge and Collin. Wdyt? I'm thinking Ridge doesn't really fit with a more common name like Collin. But that's just my taste: I like to have twin sets where both names are "equal", both so they go together well, and the twin with the lame, common name doesn't feel cheated because his/her twin got the awesome name. But that's just me.