I think having both at once is possible IF you are healthy, already strong, don't have underlying conditions (lung, heart, diabetes, etc.)
BUT things can go wrong. My (healthy) friend suffered low sodium and unstable BP after surgery and lengthened recovery. It would have been disastrous if both hips were involved since it limited her ability to get up and moving after surgery. If you get an infection after surgery, will it affect both hips? If one hip has a problem during surgery that might compromise rapid mobility, will you need to go to a rehab facility? For how long?

Other considerations - Do you have ready, willing and able help at home? You will need help with the activities of daily living for at least a couple weeks. Is your house easily adapted to toilet seat riser, shower bench and easy access to the outdoors and your car? You would not believe how difficult going up or down even 1 or 2 steps can be if both legs are affected.

When I asked about doing both at once at age 54, my surgeon was horrified. We did them 6 weeks apart to meet a "schedule" in my head, and in hindsight, even that was too close - my body was not yet recovered from the "insult" of the first surgery when I had the second.

Everyone has their own comfort level, and schedule. If you have had major surgery before and know how your body reacts, think about double the impact and ask yourself if it is a good idea for you.
Sue