Mix yellow cake mix as directed on box.

Divide batter into two bowls; add 1/2 small box of one jello into one bowl of batter and mix; in the second bowl add 1/2 small box of the other flavor of jello to second bowl of batter and mix well.

Pour each bowl of batter into a greased and floured 9 inch cake pan. Bake as directed on package. This makes two layers.

Cool completely.

Place 1 layer on cake plate, top with Cool Whip; top with second layer and frost the entire cake with the remainder of the Cool Whip. Refrigerate at least 4 hours before serving.