Regarding birth control: are levonorgestrel and norgestrel equal mg for mg?

No and yes: Levonorgestrel and dextronorgestrel are equal components of norgestrol. Levonorgestrel is the active form the dextronorgestrel is inactive as far as the human body is concerned. So while you might think double the dose of norgestrol would be equal to a single dose of levonorgestrel, many products just list the amount of norgestrol in terms of the amount of the active (levonorgestrel) component.