I don't think you overdid anything.
I just think that things are not linear in injuries and life in general.
My "good" hip (not very good at all) was scheduled at the same consultation for three months after my first. There was no question in the doctor's mind, but to me, it felt much better than the first.
Not long after the first was done, I was doing physical therapy, and eventually, the operated side felt much better despite the healing that was going on. The second side began to complain loudly and beating cymbals because suddenly I was on a stationary bike, pumping away, or walking much longer distances than before, etc.
As my operated side got its giddyup going, my other side seemed to wither under the new movement. By the time I got to three months and the second surgery, it had had it. I was more than sure that it was time and looked forward to the relief of the procedure.
I particularly noticed it when walking with my daughters to a restaurant at a mall. My left leg was walking along with no problem, my right was trying to keep up, when it hit the ground before it "had" to. I had a huge shock of pain distribute from my hip to everywhere. I grunted in pain, and stopped. My daughters had a scared look to them, and I told them ... just one more week.
So to me, it's probably a combination of things - more is being asked of the joint now that you have one strong side, the deterioration is not linear, and the pain from the first may have masked what the second was doing.
None of it is good, and all of it leaves with the operation, so for me, the second (having had the good experience of the first) was a godsend.