Heat oven to 350°F (325°F for dark or nonstick pan). Spray bottom only of 13x9-inch pan with baking spray with flour.
In medium bowl, stir carrots and coconut with 3 tablespoons of the dry cake mix. In large bowl, beat remaining cake mix, the oil, water, cinnamon, allspice, eggs and oranges with electric mixer on low speed 30 seconds, then on medium speed 2 minutes, scraping bowl occasionally. Stir in carrots and coconut. Pour into pan.
Bake 41 to 46 minutes or until toothpick inserted in center comes out clean. Cool completely, about 1 hour.
In large bowl, beat cream cheese on medium speed until smooth and creamy. Stir in frosting until well mixed. Spread frosting over cake. Sprinkle with pecans (or top with additional mandarin orange segments just before serving). Refrigerate 30 minutes before serving. Store covered in refrigerator.