If you are thinking of getting another dog, make sure that your first dog is under control before a multi-dog household is established.
Do dogs learn from each other? The answer is absolutely, but not in the sense that Dog A would have to watch Dog B participate in obedience classes in hopes that Dog A learned to heel. Dogs feed off each other and are always communicating which means information is constantly sent back and forth. Even though dogs learn from each other it is still up to us to ensure that they are learning the correct information from each other.
Dogs are wonderful communicators and teachers for each other and we incorporate them into our training programs. But the key thing is to make sure you have correct dogs doing the teachings.