Place a rack in the center of the oven and preheat the oven to 350oF. grease two 9-inch round cake pans.
Place the cake mix,mandarin oranges, and juice(from pineapple),melted butter,oil,and eggs,in a large mixing bowl. Blend with mixer for about 1min. Stop to scrape down the sides of the bowl. Increase speed to medium and beat 2 to 3mins more. Batter should look well blended and the oranges should be broken up in the batter.
Divide the batter between the prepared pans, smoothing is out with spatula.
Bake until golden brown and spring back when lightly pressed with your finger, 24 to 27 mins.
Remove pans and place on wire racks to cool for 10 mins. Run knife around edge on pan,evert onto rack, then evert them again, so that cakes are right side up.
While cakes are still warm, poke holes in the top of each layer with a toothpick or wooden skewer. Pour the pineapple juice over the layers so that the cake soaks up all the juice. Let cool for 30 mins.
Prepare frosting: Place the thawed whipped topping, pudding mix. coconut, and the drained crushed pineapple in a large mixing bowl. Stir with a wooden spoon until well combined and the pudding mix has dissolved.
place one cake layer,right side up,on serving plate. Spread the top with frosting. Place the second layer, right side up, on top of the first layer and frost the top and sides of the cake with clean. smooth strokes.
Store this cake, lightly covered in waxed paper, in the refrigerator for up to 1 week.