Discussion checkpoints are an excellent way to inform students of the required replies and their due dates. It is possible for those due dates to occur in more than one module (or more than one sequence within a module). The discussion can be added repeatedly, with module rules for "contribute to the page" measuring the initial post and "mark as done" measuring the replies. This does not change the header (or instructions) of the module entry, and so it may look to students as if the reply entry has the same expectation as the initial post.
Adding the discussion checkpoints separately to the modules ("Discussion checkpoint: initial post" and Discussion checkpoint: replies to classmates") would allow students to be reminded of the specific action and due date with a label that would help the students understand the different expectation associated with that module entry.
