If they are a per and already bonded should make things easier on that end - my dog hated our second puppy for a while. I personally love having two dogs and I also like knowing that when Im not home they keep each other company. I think really the difference from 1vs 2 is well, double training, food, vet bills, responsibility but its also double fun; my dos are small too one is yorkie/pom and the other chihuahua/dashund.
Not sure as a first time owner as i have had dogs since i was a kid, but, sometimes it can feel a bit overwhelming but for the most part its the best thing in the world to have the little monsters around.
Dogs don't need to talk, their life is their message ~ unknown.
"The greatness of a nation and its moral progress can be judged by the way its animals are treated." ~ Mahatma Gandhi