I was suppose to have foot surgery on both my feet for bunions and had the surgery day all scheduled. My doctor called and said he would only be doing one foot at a time. My right first and then my left. The reason for this is that he performed double foot surgey on one of his patient and then there was a fire in their house. I guess the person couldn't get out fast enough and had some smoke damage done to their lungs. Not trying to be a downer but just something to consider if you are going to have both feet done at the same time.
From what i understand most docs will only do one at a time -- for the reason you posted as well as the fact that there is more chance of injuring yourself if you are gimped up on both feet at once. I would strongly recommend that people do it one at a time (you are more mobile sooner too that way!)