I would like to show how I did it through the new functionality to demonstrate its work:

1. I put First name and Last name of student from the original request into the search fields and find the account created by mistake by the student: 

 - this is an account with e-mail 1812010006x@kindai.jp.ac. So, you can see exactly where the student made a mistake. To understand that the account belongs to the same student, you can look at the percentage of coincidence ("Match" column), but you need to visually look at First Name, Last Name and E-mail in the table found.

2. I went to the Progress Management tab, put the account opened by mistake in the "From" field, the main account in the "To" field: 

3. After I clicked on the "Merge" button: 

 - it's done.