I think there are other ways to mirror a person other than physically being their mirror!

I notice the big difference and impact for me is the tone of a therapist's voice and how it changes to either match mine or the type of discussion we're having.

One time, a therapist and I wore the same sweater (just different colours). I commented jokingly that he didn't have to work so hard to mirror me in session. He looked flabbergasted that I said that and said that he mirrors other clients, but its not something he does with me. Then it was my turn to be like, whaaat?