Can both hips be replaced at the same time?
Yes, both hips can be replaced at the same time; this is called a bilateral hip replacement. Some advantages to the bilateral hip replacement include only having to go under general anesthetic once, a shorter overall hospital stay rather than two individual ones, and one rehabilitation. Drawbacks include that it can be harder to recover from two replacements at once, and some studies show a higher level of complications among patients with bilateral replacements.
Only your doctor can decide which is best for you.
Harlan C. Amstutz, MD, et al. Resurfacing THA for Patients Younger than 50 Years Old. In Clinical Orthopedics & Related Research. Vol. 460. Pp. 159-164.