I agree with BarkingDog that as long as you properly introduce the dogs and ensure they are not left alone together until you are confident there will be no serious conflict, two or more dogs can be great. I've owned a single dog
as well as multiple dogs
and have found pros and cons to each. It is really a personal choice for you and of course you need to remember you will double your feeding expenses and vet bills which may or may not be a factor for you.