A Spoonful Each Way

Two identical mugs sit on a counter: one holds $200$ ml of black coffee, the other $200$ ml of milk. You transfer one tablespoon of coffee into the milk mug and stir thoroughly. Then you transfer one tablespoon of the resulting mixture back into the coffee mug. Is there now more foreign coffee in the milk mug, or more foreign milk in the coffee mug — or are the two contaminations equal?