How does the BahnCard 25 and 50, 2nd class = 1st class special offer work?

When booking with a second class BahnCard, simply select a first class BahnCard and a first class ticket. This gives you a discount on the first class ticket price similar to that of your own BahnCard 25 or 50. You must then present your second class BahnCard on the train in combination with your first class ticket.