ConfigsvrCoordinators (such as SetUserWriteBlockModeCoordinator and SetClusterParameterCoordinator) call insert a coordinator state document to initially checkpoint the operation on disk. Since the write is using a concern with timeout, it could happen the following:

1. Coordinator starts and tries to insert the document
2. The document is locally written but not yet majority committed
3. The write concern timeout is hit
4. The coordinator retries
5. The retry fails because the document had already been inserted so a DuplicateKey error is thrown