Why not make one from scratch...since it's for a special occasion? It's really not hard and only takes about 5 minutes longer.
I wouldn't combine the 2 mixes....a red cake uses very little cocoa powder and uses a different method of leavening than a devil's food.
You could put halved marischino cherried between the layers and more on top.
Linda C

Red Velvet cake
2 tablespoons unsweetened cocoa powder
2 ounces red food coloring ( that's one whole small bottle)
1 cup buttermilk
1 teaspoon salt
1 teaspoon vanilla extract
1/2 cup shortening
1 1/2 cups white sugar
2 eggs
2 1/2 cups all-purpose flour, sifted
1 1/2 teaspoons baking soda
1 teaspoon white vinegar

1 cup milk
5 tablespoons all-purpose flour
1 cup white sugar
1 cup butter
1 teaspoon vanilla extract

DIRECTIONS
Grease two 9 inch round pans. Preheat oven to 350 degrees F (175 degrees C). Make a paste of cocoa and food coloring. Set aside.
Combine the buttermilk, salt and 1 teaspoon vanilla. Set aside. In a large bowl, cream together the shortening and 1 1/2 cups sugar until light and fluffy. Beat in the eggs one at a time, then stir in the cocoa mixture. Beat in the buttermilk mixture alternately with the flour, mixing just until incorporated. Stir together baking soda and vinegar, then gently fold into the cake batter.
Pour batter into prepared pans. Bake in the preheated oven for 30 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow to cool completely before frosting. Refrigerate if using cream cheese frosting.

I just made one this past weekend and it was WONDERFUL!
its from scratch too.

Southern Red Velvet Cake Recipe courtesy Cakeman Raven, Cakeman Raven Confectionery, NYC
Vegetable oil for the pans
2 1/2 cups all-purpose flour
1 1/2 cups sugar
1 teaspoon baking soda
1 teaspoon fine salt
1 teaspoon cocoa powder
1 1/2 cups vegetable oil
1 cup buttermilk, at room temperature
2 large eggs, at room temperature
2 tablespoons red food coloring (1 ounce)
1 teaspoon white distilled vinegar
1 teaspoon vanilla extract

Cream Cheese Frosting, recipe follows
Crushed pecans, for garnish

Preheat the oven to 350 degrees F. Lightly oil and flour 3 (9 by 1 1/2-inch round) cake pans.
In a large bowl, sift together the flour, sugar, baking soda, salt, and cocoa powder. In another large bowl, whisk together the oil, buttermilk, eggs, food coloring, vinegar, and vanilla.

Using a standing mixer, mix the dry ingredients into the wet ingredients until just combined and a smooth batter is formed.

Divide the cake batter evenly among the prepared cake pans. Place the pans in the oven evenly spaced apart. Bake, rotating the pans halfway through the cooking, until the cake pulls away from the side of the pans, and a toothpick inserted in the center of the cakes comes out clean, about 30 minutes.

Remove the cakes from the oven and run a knife around the edges to loosen them from the sides of the pans. One at a time, invert the cakes onto a plate and then re-invert them onto a cooling rack, rounded-sides up. Let cool completely.

Frost the cake. Place 1 layer, rounded-side down, in the middle of a rotating cake stand. Using a palette knife or offset spatula spread some of the cream cheese frosting over the top of the cake. (Spread enough frosting to make a 1/4 to 1/2-inch layer.) Carefully set another layer on top, rounded-side down, and repeat. Top with the remaining layer and cover the entire cake with the remaining frosting. Sprinkle the top with the pecans.

Cream Cheese Frosting:
1 pound cream cheese, softened
4 cups sifted confectioners' sugar
2 sticks unsalted butter (1 cup), softened
1 teaspoon vanilla extract
1/2 - 1 cup Chopped Pecans

In a standing mixer fitted with the paddle attachment, or with a hand-held electric mixer in a large bowl, mix the cream cheese, sugar, and butter on low speed until incorporated. Increase the speed to high, and mix until light and fluffy, about 5 minutes. (Occasionally turn the mixer off, and scrape the down the sides of the bowl with a rubber spatula.)
Reduce the speed of the mixer to low. Add the vanilla, raise the speed to high and mix briefly until fluffy (scrape down the bowl occasionally). Add pecans, mix in. Store in the refrigerator until somewhat stiff, before using. May be stored in the refrigerator for 3 days.

Yield: enough to frost a 3 layer (9-inch) cake

Southern Living had a recipe for a made from scratch one in the Dec.07 issue and there is also a multi layered one in a past Christmas issue - maybe you could google and find it.

Anyway, I bake one using the Duncan Hines mix, baked it in a bundt pan, used can cream cheese icing with a little peppermint extract mixed in then sprinked the top with crushed candy canes. Actually made two last week and they were gobbled up. The idea to use the peppermint was in the Southern Living magazine.

I think if you do a search here on this forum, someone else asked about red velvet cakes or maybe Christmas cakes. Check out the Recipe exchange forum too.

Thanks for help, everybody. I think I WILL make it from scratch. Will let you know how it turns out.

chery2