Not a stupid question, because it can be done either way:
If you dose kalkwasser (Calcium hydroxide or lime) you are ultimately adding both Ca and alkalinity. This is because the hydroxide ion reacts with dissolved carbon dioxide from the air to form carbonate (alkalinity is a mainly related to the carbonate ion concentration). So really this is ideal, except that it's often hard to meet the tank's demand with kalkwasser alone.
If you are dosing pretty much anything else for alkalinity (sodium carbonate, sodium bicarbonate, or half of any 2-part dosing system) then you still have to dose calcium separately.