I am hiding from this post. I can barely train one. And that's only if there are no rabbits, birds, raccoons or foxes anywhere within a five mile radius of my back field. Duke, you have my utmost respect, buddy.
I have 2 dogs. Individually, they are pretty good. And even together, they aren't bad. But if something goes south, then 2 dogs is more than twice as hard as 1. If one sees something that sets it off, the other one will pick up on it and then they encourage each other. It's the 2 dogs plus the pack mentality. Also, the subordinate dog becomes braver when he's with the dominant dog. And the Dominant Dog is quicker to puff out its chest.
But it would be cool to be able to do a bunch of obedience exercises with 2 dogs. But I would think they should be on the same side.