Watchman IDs are a form of serial number
The Watchman ID is a unique identifier used by Watchman Monitoring to sort and store reports from each monitored computer. The Watchman ID is randomly generated during the installation of the Monitoring Client, and is meant to be unique to a computer.
A Watchman ID looks like this, beginning with the date of installation, then ten arbitrary characters:
In the case where an OS is migrated to a new computer, the Watchman ID, of course, will be copied. In these cases, the Watchman Monitoring server will see the ID coming from more than one computer, and instruct them both to rekey.
The original record will become hidden, and serve as a placeholder for any additional computers with the same ID to rekey themselves as well.
Watchman ID and Mass Deployment
When imaging computers, the best practice is to add Watchman Monitoring as a post-restore, or first-boot action. This allows each computer to generate its own WatchmanID on its actual first day of service.
However, with the Rekey feature in place, it is acceptable to install Watchman Monitoring on a computer destined to be the Golden Master. The Watchman ID on the master image will end up as a hidden record on the server, instructing all resulting computers to generate a new WatchmanID as they report.