If you were not expecting to see the Other Devices in iCloud alert when you enabled iCloud Sync, do not be alarmed! Restoring your device, or upgrading macOS or iOS can cause your device to be identified differently in iCloud. While it may be the same physical device, it may appear to be from a new device in iCloud. It is also possible that logbook data from an old device was not removed from iCloud. If your device already has your current logbook, you can choose Restart iCloud Sync to avoid syncing with existing iCloud data.