It is possible for multiple sections of a class to function as a single full-online or enhanced class.
Banner will create class shells for each of the affected sections and populate them with enrolled students. However, the designer can place all materials in one of the sections-- the designated "Main" section-- and not need to maintain the other sections. The students from all the sections will appear to be in the "Main" section and can interact with one another. Effectively, this is Banner's way of automatically doing what some desginers once did manually: dump all their students from multiple sections into one big happy shell for ease of class management.
It Is Critical that cross-listing be set up before any student coursework is done. After classes begin, do not ask for multiple sections to be cross-listed. Please consult with IT for options.