If you're using a standard home recipe, and not a large commercial recipe doubling everything tends to work fine, or at least it has in my experience. I would not venture to comment on larger batch recipes, and Nicole's comment may be more appropriate. In general I tend to like to work a slightly moister dough so they can puff up a little more easily even with a standard single batch, so I'd be a bit generous with the liquid, but that's my preference in any case. Best of luck.
When doubling a baked good recipe the problem most people run in to is things like baking powder or baking soda, all other ingredients can be doubled except these two. The ratios I have normally seen used when determining how much to use when doubling a recipe is:
1 to 1-1/4 teaspoon baking powder per cup of flour 1/4 teaspoon baking soda per cup of flour
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1 to 1-1/4 teaspoon baking powder per cup of flour
1/4 teaspoon baking soda per cup of flour