by Davo Smith.
When students open the assignment, after they have been allowed a resubmission they are, last time I checked, offered a choice as to whether they want to start a fresh submission, or to include their original submission in the resubmission. In different situations, different choices are appropriate, but it is up to the student to decide. Maybe this just needs explaining to the students (unless that option has been removed since I original wrote the feature).