Combine: In large mixing bowl, combine cake mix, 1 package pudding mix, lemonade concentrate, oil and eggs. Using an electric mixer on medium speed, beat 2 minutes. Add lemon-lime soda, mixing until just blended.
Transfer to a greased and floured 13x9-inch baking pan. Bake in a preheated 350°F oven 35-40 minutes or until a knife inserted in center comes out clean. Remove from oven and allow to cool completely
Meanwhile, in medium mixing bowl, combine remaining package of pudding mix and milk. Using an electric mixer on medium speed, beat 2 minutes.
Create: Allow pudding to stand 5 minutes or until fairly set. Fold in thawed whipped topping. Spread over cooled cake. Keep refrigerated. To serve, garnish with fresh blueberries and mint leaves, if desired.