I’m not sure I understand the comment above. Since when is re-sitting for an exam punishment? Had you said it was a nuisance, I’d agree. Had you said it was unfortunate, I’d agree. Had you said it was an inconvenience, I’d agree. Had you said it made people angry, I’d agree. But I fail to see how it’s a punishment.

If the original exam has been contaminated by massive distribution of the questions and/or answers, it can’t be considered a valid measure of student’s knowledge any longer, regardless of whether any individual student cheated or not. That’s a fact. I have to presume that any student who took the exam without having cheated on it still has possession of the knowledge with which he or she walked into the first exam. With that knowledge, that student should be able to replicate, or ever better, his or her original grade. Which would make re-sitting for the exam an opportunity as well as a nuisance, as well as unfortunate, as well as inconvenient, as well as a source of anger.