Stop repeat / duplicate log in of participants

HI There

My Adobe connect seminar room as recently encountered a number of participants logging in multiple times into the room.

The appear like John smith , John smith2 etc

Sometimes there can be 3-4 of the same person logged into the room... This isn't a problem when there is a small number in attendance, however it does cause a problem when the number of students is clsoe to our limted quota of students attending..

We have a quota of 200 attendees allowed... However recently we have around 170 students but becasue a large number had duplicate log ins, manu other students were unable to access the room.

I'm wondering is there a way to prevent multiple log ins where if a student logs in with their credentials you cant log in with the same credential twice 

Thanks