It sounds like you have "alternative" programs set up on your site! This means that your site is set up so that someone may enroll in or the other of these programs, but not both! In this case, you can help by doing the following:
Go to People > Find a Person
Enter search information to find the reader
Click three-prong icon next to the reader's name
Un-enroll them from the incorrect program by clicking again on the checkmark under "Enroll" for that program.
Enroll them in the correct program by clicking on the now visible empty box for the correct program.
NOTE: You cannot unenroll someone who has already completed a program.