Mix sugars, peanut butter, shortening, margarine and egg. Cover and refrigerate at least 3 hours.
Heat oven to 375°. Shape dough into 1 ¼-inch balls. Place about 3 inches apart on ungreased cookie sheet.
Flatten in crisscross pattern with fork dipped in flour.
Bake until light brown, 9 to 10 minutes.
Cool 2 minutes; remove from cookie sheet.