Unless approved by the department chair, a student may only register for one section of a given course in a given session.
With the plateau fee structure, students are attempting to boost their GPAs by taking the same course multiple times in one semester. For example, a native speaker of Spanish might attempt to register for 3 different sections of Spanish 1001. A student attempted to do this during the summer semester and demanded to see the written rule prohibiting multiple attempts in the same semester. This is not a change in practice but merely a codification of existing practice.