Cheating was defined as any falsification of information. Scientists are judged by their written records, reports. The same standard was applied to an answer sheet. Cheat Checker is also offered as a service for machine scorable tests. It originally processed each version of a test individually.
Recent experience indicates students are defeating the security promised by multiple-form tests.
The current version of Cheat Checker processes multiple forms of a test as one test. The use of any device to establish cheating has it limits. Even when cheating is confirmed, there are limits to the use of the information in an educational setting that supports learning from past error. My own policy was to inform a class on the first day and on each test that any answer sheet that failed the test for independent marking would receive a score of zero. When cheating is relatively easy to detect, the penalty and process of applying it can be relatively simple.