If you have the same child name repeated (particularly if you are migrating from your older class):

 Delete the repeated students from the class: 
  • Navigate to your class
  • Click the manage icon on the top
  • Click Students tab
  • Click on the Student's name who needs to be removed
  • Click "Remove From Class"
  • Click Remove Student Only from the pop-up message

Note: The Student Removed from Class Successfully message pops up. Now, the student no longer exists in the list.