How to Walk Two Dogs
Before you try to walk 2 dogs at once, you should train each dog to walk without pulling individually. To do this, start by walking 1 of the dogs and stop the walk every time it starts to pull. Only resume walking once the leash goes slack, which will teach it to stay near you. Practice this technique with each dog individually until both have learned it well. Then, try walking the dogs together. If the dogs get too excited walking together, have a friend hold 1 leash until they're used to being together.
Take one dog for the loose leash walk at a time. You want to train each dog to obey the leash pull signal first before getting them together. Remember to carry necessary supplies with you as you would for any dog walk such as the leash, water, poop scoop, and disposal bag. Typically, you should walk up front with your dog. This won't be as easy when walking two dogs at once, but will be better for the training phase. Think about using a shorter leash during this phase if you need more handling control of each dog. Allow for 30 minutes to one hour for the walk. Practice loosening the leash and tightening it for each dog. You want to do this for one dog at a time. As you proceed with the walk, if the dog shows signs of pulling, you need to stop walking. Resume the walk when the leash goes slack again. Repeat the loose and tight leash walking technique. If you keep doing this during the session then the dog should learn that it can only move when the leash is loose. Make sure anyone who walks the dog knows to use this technique so the lesson is reinforced. Use the loose leash technique in other locations. This training method should be used even in situations other than the daily walk--whenever the leash is on. This will allow both dogs to continually absorb the lesson and get comfortable with walking calmly with the leash without pulling. Reward your dog during and after the walk. This is positive reinforcement to the leash lesson, but should not be excessively long in duration. Allow the dog to relieve themselves, and sniff in safe areas during the walk. But don't let this go on too long. Set a meal and water for the dog as a reward when returning home. Use a clicker, word, and treat to mark the heel position. The heel position is when the dog's shoulder is lined up with your legs. The clicker is optional, but using that or a simple word will help in the reward phase. Clickers can be found in most pet stores. You want to get in the habit of rewarding the correct position frequently so the dog remembers it. Deliver the treat near your leg in the area you want the dog to walk. Get your dog to catch up to you and heel. During a leash walking exercise, if your dog walks out ahead, try turning around quickly and getting the pet's attention. Do something such as calling the dog's name and moving in the opposite direction to get the dog to follow you. When the dog catches up, and assumes the heel position, use the sound and treat reward technique. Add the word "heel. " Once the dog is reliably walking by your leg into position then you can add the command word. Do this in low distraction areas at first. You might want to try this in your home before attempting it on a walk outside. Remember to reward the correct behavior and position with the clicker/word and treat. Use a release word. This should be a simple command like "free dog" that lets the pet know he can walk again. Work this into the training of the heel command. Don't allow this to ruin the leash control you have over the pet. Vary the time between the heel and release commands. Do this during the heel training of each dog. This will teach the dog to respond to the command and not just expect a routine. Remember to use the reward techniques for correct behavior. Practice loose leash and heel techniques with both dogs. Do this in low-distraction areas. If one or both dogs appear distracted you should try more practice with them individually. You can also try having a second walker more gradually introduce the second dog by walking the other pet in parallel on their own leash. Gradually bring the dogs closer until only one person is holding both leashes. Use loose leash techniques for most of the walk. This is usually fine once both dogs are trained. With loose leash techniques the dogs can sniff and explore a bit. Use heel commands to avoid major distractions such as another dog or traffic. Mix in loose leash, heel, and relaxation with the walk. Continue to use the loose leash and heel techniques until the dogs become accustomed to it. But don't forget to rest them and let the pets enjoy the walk. Find shady spots, dog welcoming parks, water spots, and the like where your dogs can rest and explore under your supervision. With two dogs under your care it will take more effort to watch that they don't get into trouble with other animals or people. You will need to take extra care watching that the two of them don't tear up the landscape such as digging holes, tearing through fences, or jumping in public water features. Reward good behavior. Keep water and treats with you for both dogs. Water is necessary for the walk, but also keep some treats with you to reward the dogs for good leash behavior and obeying commands. Make sure you're rewarding both dogs equally. Prepare a meal for both dogs when the walk is over. When returning home you want to reward the dogs for a good effort. Have enough food and water for both pets in separate bowls for each. Even though the bowls are separate you can have the eating area in the same room. This is also a good time to give the dogs a break from the leash. 
Take one dog for the loose leash walk at a time. Practice loosening the leash and tightening it for each dog. Repeat the loose and tight leash walking technique. Use the loose leash technique in other locations. Reward your dog during and after the walk. Use a clicker, word, and treat to mark the heel position. Get your dog to catch up to you and heel. Add the word "heel. Use a release word. Vary the time between the heel and release commands. Practice loose leash and heel techniques with both dogs. Use loose leash techniques for most of the walk. Mix in loose leash, heel, and relaxation with the walk. Reward good behavior. Prepare a meal for both dogs when the walk is over. 