Huh? Now I'm lost.

Actually, it's the other way around. The person with 50% more muscle than another person of equal weight burns more calories simply because muscle is metabolically active tissue. Put another way, muscle burns more calories than fat does.

Your math is flawless - your logic isn't.

In one case you have 20 lbs of muscle burning 50 calories on average. In the other case you have 10 lbs of muscle burning 100 calories on average.

Can you explain to me how you managed to double that person's metabolism?

Work done = mass X distance traveled. It's the same whether you walk a mile or you run a mile. Of course if you ran for 15 min you will burn more calories then walking for 15 min, because you'll travel a greater distance.

But the total calories burned is a function of the amount of muscle you have. So no, in the scenario you present I'll argue that they both aren't having a 1000 calorie workout.

My math was that each pound of muscle expends that much energy on average. So for the person with 20# muscle and a 1000 calorie workout, each pound expends 50 calories, yet the person still does 1000 calories of work.

You can argue it all you want. Work done is work done.

MOST people do their BMR x 1.2 (for dietary + sedentary) and then add calories burnt on a per workout basis to figure out their calorie expenditure for a week. I get that you're saying that the BMR of a more heavily muscled person is going to be higher which makes them spend more calories ALL the time (regardless of workout). Once you subtract out that they are spending more calories all the time (which is how people figure it), they are still doing the same amount of work per 1000 calorie workout.

Or are you going to argue that the muscle on the person with 10# of muscle instead of 20# of muscle, that the muscle is the same amount of "strained" after the workout?