The IER launched an investigation following media reports that a candidate cleared the test she did not attend on Nov 18.
The result of the admission test of the evening Masters of Education (MEd) course was published on Wednesday.
The IER in a statement of Friday said a candidate named Nasrin Hossain sat in absent candidate Pallabi Baroi's seat by mistake. Nasrin also mistook her roll number 2558 for Pallabi's 2553 and put it on the answer sheet creating the confusion.
In the revised result, Nasrin passed and Pallabi was dropped from the list of successful candidates following Nasrin's complaint, it added.
Earlier, after seeing her roll number among the passed candidates, Pallabi's brother wrote to Dhaka University authorities.
He said she could not sit the test due to illness but her name appeared on list of passed candidates.
He asked the university to check if there was any fraudulent activity involved in it.