The pediatrician office I went to in my childhood was set up so that there were two wings to it with the reception area in the center. If you were a boy, you were called to one wing and a girl, were called to another wing. This made sense because back in those days, modesty wasn't what it is today. I know that sounds crazy considering how people dress out in public but in terms of medical modesty, it is ironic that back in the days when you were expected to dress nice out in public, your clothes were either completely off or at most, it was just underwear on at exam time.
Now that that scenario has been set up, as you can imagine, it was common to be seen by other patients and their parents as they walked to and from their exam rooms in the hallway. In the boys section of my pediatrician office, there was a common scales in the hallway, behind the reception area where we were weighed in our underwear so we were often seen that way by others besides the doctors and nurses. The doctors and nurses otherwise were very good about keeping the door closed when patients were in the exam rooms.
In case anyone is wondering about situations where there are a brother and a sister, I don't recall seeing them being called back to the exam rooms together. I only had a brother and we were pretty much always examined together but I am sure that is because my mother did not want to have multiple doctor visits on top of her already busy schedule.
One time, way back in my childhood, I do remember being at the hospital emergency room late one night when my brother had an inner ear infection. I remember having to go to the bathroom and I left the curtained off area where my mom was with my brother. After I finished, I went into the wrong curtained off area and a poor boy about my age was on his side, in tears, having his temperature taken (not in his mouth). I guess he was in so much pain, he couldn't hold a thermometer under his tongue. His mother and the nurse were both startled that I walked in and I immediately felt bad, said I was sorry and left. Oops.