In separate bowls, prepare two 17.5-ounce bags sugar cookie mix as the label directs for cut-out cookies; beat 3/4 teaspoon red gel food coloring into one batch and 3/4 teaspoon blue gel food coloring into the other. Form each batch into a 14-inch log, wrap in plastic wrap and freeze until firm, about 30 minutes. Slice the logs into 1/4-inch-thick rounds and bake as directed; let cool. To assemble, layer the cookies with whipped cream on a platter, alternating colors. Refrigerate up to 2 hours so the cookies soften (but don't bleed). Sprinkle with red sanding sugar.