Hi there, that completely depends on your dogs. If they get on well and don't pull on the leash you can have both on one side. If they do pull you might want to walk them separately anyway to teach them good leash walking behavior. If they pull sometime but not all the time you might want to have one on each side, so you can correct their behavior.
I agree with LetsPlay, it does depend on your dogs. I have 2 large breed dogs and as such will only walk with one on either side of me as I feel I would have more control of them this way....should the need arise. Generally it doesn't really matter, it's whatever works for you and your dogs.
Thank you for your comments - that helps a lot. They seem to do better when one is on each side but I wasn't sure if that was correct. Now if I can just get them to be good on the leash!
Hi again, if they are both pulling on the leash I would recommend to walk them separately. That way you can stop walking the instant your dog starts to pull without confusing the other one, who might have been good. Every time your dog pulls stop and turn around. He will need to learn that pulling doesn't get him anywhere, instead it makes you stop. Good luck. John