Preheat oven to 350 degrees and line a muffin pan with paper liners. With a mixer at low speed, mix together the eggs, butter, milk and yogurt. Add the dry cake mix and stir until smooth.
Divide the batter evenly between two bowls. Pour the blue dye into one bowl and the green dye into the other bowl. Blend dye thoroughly into batter.
Spoon batter into cupcake liners, alternating between colors. Swirl the top of the batter slightly with the back of the spoon.
Bake 17-20 minutes until a toothpick inserted in the center comes out clean. Cool completely on a wire rack.