I really love having two, they are so fun to watch together. And they really do form a special bond. I agree with 
mjharpst I think that Copper is a better dog since he has had a companion. He was really sick and when we brought home his friend, Rocky, he gained a healthy appetite and would play for hours (he was never a very active puppy) I really think that the second dog brought life back into Copper. As far as your townhouse, and no fenced yard, my dogs love to explore and go on leashed walks, especailly if they have a partner in crime

 I am sure that what ever you are doing now for your fist baby would work equally as well with two. I hope that you are able to get a second baby and make it work for your situation.