probably because they are so frozen and dense the microwave cannot evenly cook both adequately.
By Harry (Guest Post)
08/08/2008
Microwave ovens come with different wattages meaning the higher the wattage the less time to cook. So the food manufacturer takes a lower wattage to figure time to cook one item, say 6 minutes. The more items in the oven the longer it will take to cook and the food may not be cooked uniformly. That doesn't mean two items will cook in 12 minutes. You could put two items in the oven but the results may not be as good as cooking one item at a time. You could cook one item at a time then place both items in the oven and reheat. That may work also. You will have to experiment to get the correct time to cook two items.