Drain mandarin oranges and reserve liquid. Add reserved liquid to a liquid measuring cup (there should be about 1/2 cup) and fill with water to measure 1 cup. Prepare cake mix according to package directions, using the juice and water mixture in place of the water called for on the package. Bake in two greased 9-in. round baking pans according to package directions. Cool for 10 minutes before removing from pans to wire racks to cool completely. , In a large bowl, whisk milk and pudding mix for 2 minutes. Stir in pineapple. Spread 1 cup between cake layers., In a small bowl, beat cream cheese, sugar and vanilla until smooth. Beat in 1 cup whipped topping. Fold in remaining topping. Spread on top and sides of cake. Cover and refrigerate for 3 hours or overnight. Decorate with mandarin oranges prior to serving.