If you have enough space between them, and you let the oven really properly heat up (most people don't heat their ovens nearly long enough), it will only take 10-15% longer (so for a 90 minute roasting time, figure 100-105 minutes).
One of my favorite adages is that it takes as long to roast two as it does one, and then you've got bags of lovely roasted chicken meat in the freezer as well as an even bigger batch of stock on the other end. It may take a bit longer given the greater mass in the oven, but negligibly so. Just do it!
2 Comments