My impression is that it is harder for dogs to learn both, but Thor has it down, and it's really nice to have all the options.
Also, I just have to stick this brag in here: Thor now poops on command! I tell him "Potty" for pee, and "BM" for poop. It's a load off (hee!), because he would sometimes go in a random spot when I took him to the office (which I suppose is an argument against training them to go indoors and outdoors). Anyway, now I just tell him to go before we go into the office, he gets a big treat, and everyone is happy.
I also wanted to say - reading back on these potty training threads, I remember how long and hard the slog was to get Thor potty trained. I sometimes honestly thought he would never get it. And it is soooooooooo nice to be on the other side of that mountain. Don't give up.
