I did that a lot as a kid, as well as having to scratch e.g. my left arm if I’d just scratched my right arm. I had to put my first step on a new surface with my left foot and the last with my right, and I had a system of sort of aping something I’d just heard by grinding my teeth, which I still sort of do sometimes but only in my head because my teeth have grown in such a way that I can’t really do it any more.