My experience is the opposite. Both my dogs are 'reactive' to certain dogs and when they're together it's more than double the work to control them. I wouldn't add another dog unless you're willing to put A LOT more time and energy into taking care of two dogs. In my experience, you do have to train them separately, walk them separately, let them out separately etc. And sometimes even if one isn't reactive and the other is, they both end up feeding off of each other. I love both my dogs, but most of the time I wish I only had one pup. I got a second dog to keep the other company and so that he would have a friend...but it's been hard on all of us...