I understand that the Higher Education Authority have been in contact with the universities and designated institutes regarding this matter.
With one exception, the colleges have advised that no such evidence is available. Dublin City University carried out a comparative study of students entering the four years 1983-1986. They found that students who entered on the basis of a leaving certificate result from more than sitting of the examination were significantly in a statistical sense more likely to fail first year examinations (summer and autumn) than those who entered with similar points obtained on one sitting only of the leaving certificate.