One person's name is appearring multiple times in the meeting

Problem:  I have everyone register for the meeting. The first-person name who registers name (for example A B) is being used automatically by people who come into the meeting.  So, I can end up with 4 people in the meeting named A B.   This makes it impossible to know who is in the meeting defeating the reason purpose of having people register in the first place.  It could be people who have no Zoom profile account that come into the meeting with the A B name. Is this a known problem?  How do I correct this problem?