Since Macs only report MAC address of enabled and connected interfaces, please consider changing the unique identifier to something like the UUID.
Pros: UUID only changes if the hard drive is changed. No duplicated machines with removable or disconnected interfaces (all portable Apple products). More accurate numbers for reports.
We recommend contacting development about this at support@lansweeper.com. What you are asking may not be implemented to be honest, as this would require quite significant changes to the Lansweeper service.