From Eileen Laber:
I am unsure about using the clicker for two dogs. When one dog is offering a behavior and the other is doing nothing, and I click and treat the dog offering the behavior, am I diluting the effect of the click for the dog that is doing nothing. Sometimes the dog doing nothing comes to me looking for the treat.
In a "training" situation, I think the dogs can figure out which dog is getting the click, but when we are just looking for the dog to do something cute, both dogs respond.
Thanks for your question. There are several answers.
1. Separate the dogs when you train.
2. While you are training one dog, treat both, each time you click. One is getting clicked for the behavior, the other for lying down or for being quiet while watching.
3. Call out the name of the dog you are clicking, at the instant that you click some random behavior that is cute. After some experience, the other dog may discover that it didn't get clicked because it wasn't doing the thing Blackie was doing. (Dolphin trainers sometimes do this by pointing at the correct dolphin as they give the marker signal.) Try to do this with both dogs, i.e., give them each a chance to understand the nature of the "named" click.
4. Ignore the problem. Don't worry about the dog that didn't get a treat when it heard the click. You should be clicking, during regular training sessions, at a high enough rate (at least 10 clicks a minute, 50+clicks in a short training session) that an occasional missed treat has no dilution effect on the clicker. Plus, dogs often place value on the direction in which you are looking, so they can figure out the click was for the other dog, because you are looking at the other dog, not at them.
5. Develop a verbal marker that is different for each dog. Then you can capture spontaneous behavior with either one, without confusing the unclicked one. Of course just seeing dog 'A' get a treat is enough to make dog 'B' come begging; you might want an end-of-session marker to tell dog 'B' "Nothing personal, but no treats available." I use the Hawaiian word "Pau" for that. If you are going to go on and really work with dog 'A', because some especially charming behavior came up which you wish to develop, crate or tether dog 'B' and toss occasional treats at random (as long as the dog is quiet).
6. Try using the Clicker+. It's perfect for training multiple animals.