Two puppies together can be a very big problem. They tend to learn more slowly, they tend to have more potty training problems, and they tend to bond with each other more than with you. Many times one dog of the pair can become over dominant and the other over submissive, or the pair become over dependent on each other and can become frantic when left alone. Often if the puppies are similar in personality they can become fierce rivals as they get older and may have to be permanently separated; these dogs will often fight to the death if allowed to mingle. Ami The Memphis Dog Coach recommends that you wait for the first dog to reach 2 years of age and then consider adding a second dog.