I am using the ATK almost no-knead recipe. You place the bread (in dutch oven) into a cold oven, and turn it on/start the timer. Can I cook 2 loaves simultaneously, or will this change the preheating of the oven too much?
It shouldn't effect the temperature too much - but I would take care to make sure there's room for both Dutch ovens comfortably. They can probably even touch, if needed - but if one is located closer to the base or rear of the oven and the other is towards the top or front, they may bake unevenly. If they both fit comfortably, try rotating the pans once or twice during baking!