I also agree that you already have the right tires for randonneuring. If you want to tweak things a little, you could consider running the extra light version up front and the endurance version in the back wheel for randonneuring.
My current set up is a René Herse with extralight casing up front and Schwalbe Marathon Racer in the back. I tried a René Herse extralight casing tire in the back and I was not happy with the tire punctures I was getting. The Schwalbe Marathon Racers are so much better in that respect while still being fairly fast rolling.
For credit card touring, Marathon Racers both front and rear will do the trick for me which, by the way, is the same tire setup I used for PBP 2015. I just preferred not to be dealing with flats in a once-in-a-lifetime event such as that one. Those tires worked beautifully for me.