I double recipes all the time.....
I think the only time that really matters is if you are making a cake recipe, where you change the size of the finished product, like trying to quadruple an 8" cake recipe to fit a 12" pan or something like that. The baking time would change, of course,which would affect the time the leavener has to work. Plus, trying to get the middle of a big cake to cook without overcooking the edges of a big cake is different than for a small cake.
But if you're going to make cookies or muffins, where you're just changing not the size, but the quantity of the finished product, like from 12 muffins to 24, I don't think the leavener is an issue.