You have 2 dogs and 1 hour. So they go out together, and they have done since they were puppies. Now both of them pull, one barks, and you get home with a sore shoulder.
Each of them is easier on their own. That is not a coincidence, and it points straight at the answer.
Why two dogs is more than twice one dog
Arousal stacks. Each dog's excitement feeds the other, and neither comes back down during the walk. You are handling a system, not 2 dogs.
They also pay each other. Pulling gets both of them forward, barking gets a response, and every lap of that loop makes the next one easier to run.
Learning happens below the level that pushes a dog past what they can manage. A double walk that is above that line from the front door cannot improve by being repeated.
Then adolescence. Around the onset of the stage dogs respond less to the cues of the person who raised them, and that responsiveness returns later. Two adolescents together have very little left for you.
Split the walks for 3 to 4 weeks
This is the whole intervention, and it is the part owners resist. You cannot teach loose leash walking to a dog who cannot hear you.
Walk them separately for the next 3 to 4 weeks, even if that means 2 shorter walks instead of 1 long one.
Make the second dog's wait boring and pleasant: a stuffed frozen toy or a chew while the other one is out.
Use the solo walks to actually train. 15 focused minutes with 1 dog beats 50 minutes of being towed by 2.
Alternate who goes first, so neither dog learns that the door opening is always about them.
Behaviour change is built from management plus reinforcement together, and splitting the walk is the management half.
Reward-based training is associated with higher reported responsiveness and fewer reported problem behaviours, and you will see it faster with 1 dog at a time.
Sort the departure, because that is where it starts
Harness both dogs in separate rooms, or one at a time, with the other one waiting behind a door or a gate.
Go out of the door one at a time. Two dogs barrelling through a doorway together sets the tone for the next 40 minutes.
Wait for 4 calm feet before the lead clips on, every time, even when you are late.
Walk the first 200 feet slowly, on a boring bit of pavement, before anything interesting happens.
Put them back together on purpose
Bring a second person for the first joint walks if you possibly can, with one dog each and a person in the middle.
If you are on your own, walk them on separate leads in separate hands, and never both leads in one hand.
Use a short, dull route for the first joint walk. 15 minutes on a quiet lane, not an hour at the park.
Pay each dog for walking beside you while the other one is there. 1 treat every 10 paces is not too often in week 1.
Stop and put distance in at the first sign of pulling, rather than waiting for the barking.
Take sniffing breaks a few feet apart. Sniffing brings a dog down where more walking does not.
End early and on purpose. A good 15 minutes teaches both dogs more than a bad 45.
Equipment and safety, plainly
Two separate leads, one in each hand. No coupler, no splitter, no double-ended attachment between 2 adolescent dogs.
A well-fitted harness on each dog, with the leads at a length you can shorten fast.
Nothing round your waist, and no loops wrapped round your hand. Two dogs pulling in opposite directions is how people go over.
Leave the extendable leads at home. Two of them at once tangles at ankle height.
If you physically cannot hold both dogs, you are walking them separately from now on. That is a safety decision rather than a training one.
It is fine if this stays the arrangement
Plenty of households with 2 adolescent dogs walk them separately for a year. They go back to joint walks once both are past the worst of the stage.
Relaxation is trained as a behaviour in its own right, in short repeatable sets below your dog's threshold. Two dogs who can settle in the same room have an easier walk than 2 dogs who cannot.
Safety note
Get help now if either dog has growled at, snapped at or made contact with the other. The same applies to any contact with a person. Stop walking them together and speak to your veterinarian and a qualified behaviour professional who works with reward-based methods. Fights between 2 dogs in the same household are not a walking problem and do not resolve by being managed harder. Two dogs tangled in 2 leads is also how owners are pulled over and dogs are hurt on roads. If either dog's behaviour has changed suddenly, book a veterinary examination. Sudden behaviour change warrants one, and pain frequently presents as a change in behaviour rather than as obvious lameness.
What to expect
Owners usually report the solo walks improving within 2 weeks, and the joint walk being the last thing to come right. Nobody can promise you a pair of dogs who walk like one, and separate walks and short joint ones are what get closest.
If more than the walk is difficult with 2 dogs in the house, the Assessment is a better starting point than any single article. It is free, takes about 3 minutes, and asks for no email address.
Today's version, in one line: walk them one at a time tonight, 15 minutes each, with a chew for whoever is waiting.