Multiple support engineers have told me that LabVIEW reuses some internal references if you duplicate a frame in a case structure and that this causes the LabVIEW diff tool to confuse and highlight different frames of a case structure when comparing two versions of code.
The support engineers recommend to always create a new case rather than copying an existing case to prevent this issue. This seems to be a fundamental flaw with LabVIEW's "duplicate" mechanism - any copies etc of objects (case structure frame in this example)should be treated exactly the same as creating a new object
