Robs pretty good in getting back to people quickly with license issues / activation etc. Personally I can't recommend KeyClone highly enough, it makes the job sooo much easier, and if you're a new multiboxer, that's important (I think anyway).

If you're only dual-boxing, I would think any class combo shouldn't be too challenging with the possible exception of two melee (ie/ warrior + rogue). So long as one or both are casters you should be fine.