When a recipe calls for baking on two trays simultaneously, it should also tell you to rotate the trays top to bottom and back to front to ensure even cooking. If you don't the top tray will be browned and cooked on top, but will remain slightly underdone on the bottom.
For someone who has issues with food, the span between Halloween and Christmas is awesome and brutal for obvious reasons, but for an all-or-nothing type of gal like me, Halloween candy is the worst. And the best. And the worst.