Yes! Students can be registered in multiple classes without having to create more than one account.
After the student has created and signed into their CommonLit account, they should go to their “My Account” page. Make sure that the student has the code from the other class they wish to join.
Under their “My CommonLit Classes” section, they should see a “add another class code” link. The student should then click on the link and enter the class code to register in an additional class.