Is is a violation of HIPPA law to disclose to one patient, that someone they know is also a patient of the same doctor's office?

Perhaps, of course when I register at my doctor, we all sign a list, everyone who visited that day has their name written down.

Also when they come out to get me, they call my name out loudly ( hard of hearing) so any and everyone in room knows who I am

Well, I know that person was not in the office at the time (I would not have gone in), or later in the day - I believe the office worker told him outside of the office that I was now a patient of the same doctor.