So I tried dual boxing diablo 2 this weekend...

Used a necromancer and sorceress. Left the necromancer to just summoning skeletons. I was able to clear the den of evil at least, but it didn't go as well as I was hoping. Moving together was harder than anticipated for anything other than going straight. Left-handing a mouse was easy for the most part, but picking spells and stats on level-up was awkward for some reason.

I'm thinking a barbarian and paladin team might work nicely together, but for the most part its just using one at a time to cover for the other one's weaknesses, while still providing nice buffs.

For anyone wanting to try, I'm warning you that it isn't easy. The game is almost completely run by mouse, and there is no /follow. There are movement intensive fights where you have to manually dodge things or you will take a lot of damage. You will probably have one character mostly serve as a buffbot, which isn't really bad considering the insane buffs in D2.

Also, from what I gather, the realms are still plagued with rampant cheating. This is making me stick with "single" player for now.