Straight from AACOMAS:
"Courses retaken at the same school or a different school for a higher grade are considered “Repeated.” If you repeated a course, mark the first attempt and each additional attempt at the same or a different institution as “Repeated”. Do not mark withdrawn attempts as a repeated course. Make sure you have entered 0.00 credits for the initial attempts. Only the final attempt should receive full credit value. Withdrawn courses and courses taken multiple times for new credit (such as physical education courses) are not considered repeated. Select “yes” and then check off each attempt at the class to mark it as “Repeated.” Only the final attempt at Repeated courses will be factored into your AACOMAS GPA. Repeated courses taken at the same school must have the same departmental prefix and course title.
While AACOMAS allows applicants to classify similar coursework from separate schools as repeated, the verification staff is not responsible for determining whether the content, course level, and credit hours are equivalent. AACOMAS staff can only correct incorrectly classified repeated coursework from the same school. In order for repeated coursework across institutions to be verified as repeated, the applicant must enter the initial attempts as 0.00 credits and mark each attempt as “Repeated” during Transcript Review. AACOMAS will not edit repeated courses across institutions after the applicant is verified."
help.unicas.com:8888/aacomasHelpPages/instructions/academic-history-2/transcript-entry/index.html
Edit: I know what I am talking about, the fact that they let you replace your courses is just odd unless it was from a totally different institution, because it clearly states here it must have the same prefix and name. Also, I do not believe you can replace easier courses with harder courses.