Don't worry, it's a normal phenomenon that you get double vision after strabismus surgery within two weeks. In general, the symptom of double vision after strabismus surgery will relieve gradually and completely disappear after half a year. If you have misgivings, you could make an appointment with your doctor for a further consultation. In daily life, you should not overwork your eyes and you should take a good rest to avoid asthenopia. Wish you recover soon.
It depends on how successful of your surgery and how long your eyes recover. Some patients will recover a week later after the surgery and some have the same symptom as you do. So it is hard to tell you how long does double vision last. What you should do is to wait and see whether this situation is getting better or not. Don't have medicine at random. If your situation is getting worse and worse and you get double vision for a very long time, go to see a doctor for help.