Why can't I put more than one in-house course on my schedule before Drop/Add begins?

We need to be sure that every resident has an equal chance of getting into a top preference course. Because of the limited number of seats in each course and because enrolling in an in-house course is required, we expect students to have a course before Drop/Add begins, but once it begins, anyone may add an additional course. NOTE: Any student signing up for more than one in-house course before Drop/Add will likely be removed from BOTH courses.