Hi Bob, You keep coming up with these great threads! At this rate the horrible January-February doldrums won't be so bad!
With the two dogs you've introduced "the eternal triangle" , how each dog relates to you and to each other. Some very serious variables at work here.
Two young dogs: worst case. They will fixate on each other and any training is only an annoying interruption in an otherwise non stop play time. You are relegated to providing dog food. The mischief that two (or more) dogs can get into is beyond anything you imagine. Serious stuff.
Best case: Solid, stable, well trained older dog who will be invaluable in showing the pup the ropes and serving as an example during training.
I've only experienced this once but it was such an eye opener; my wonderful old GSD Rose and my wife's Shelty. What ever we were training on at the time, the little Shelty was constantly looking to Rose to see the correct response and modeling off her. I never, ever had so easy and quick time of training a dog.
But Bob, you haven't said why you would be considering taking two dogs. Maybe if we knew your thinking, the advice could be more specific.
It's always important to be "Leader of the Pack" but with two dogs it's absolutely critical. From the dog's point of view, he has a willing co-conspirator in other dog, up for just about anything. The only stopper for this is your firm hand and pack discipline.
Best Wishes, Rob