If you have more than one dog, you might always keep them together. You might feed them in the same room, brush them at the same time, take them for their afternoon constitutional as a pair. Why not? Together, they are more than likely as cute as two peas in a pod.
But peas they are not. They are dogs, which means they are full to the brim with feelings. If your two dogs are never apart, they will become less and less able to be apart. In that case, when one of them has to go to the vet, say, or worse, stay overnight at the animal hospital, the other dog will be beside himself with anguish. He may whine and cry or wait by the door, a pitiful sight, enough to make you wish you'd read this years ago.
The fix is easy. A couple of times a week, no less, but more if you so choose, walk your dogs separately. Take one when you go to the bank. Take the other when you pick up your dry cleaning. Or, one day, take one for a regular walk and the other on an adventure walk, a long, long hike to a new neighborhood. Next time you take them out separately, switch off. This time the dog that got the shorter walk gets the longer walk, maybe with a stop at an outdoor cafe, or a trip to Beasty Feast for new toys.
Letting the dogs see that they are safe going out without each other, and, as important, safe staying home without each other is an important part of their training. Cute as they are together, it is essential for every dog to know that he's also his own guy, that quiet time need not be frantic time, and that seeing the world without his buddy along can be merely another way to have a good time.