The ShipGear installer will not allow multiple Admins with the same serial number to be installed on a network. If you get this error, then it is possible that the original Admin machine was shut down when the second Admin was being installed.
In this scenario, the installer does not detect the original Admin and so it allows the second Admin with the same serial number to be installed. When the original machine is restarted, two Admins with the same serial number are now running on the network. One will be recognized as invalid, depending upon the order in which the two Admin machines are started up. The Admin that is started up first will be valid.
You have a number of options for how to resolve this issue.
Option 1 : Recommended
To avoid further errors, uninstall ShipGear or the ShipGear Admin on the machine that you are not intending to use.
Option 2
To continue using the originally installed Admin, shut down the ShipGear services on both machines and then start the ShipGear services on the original Admin first. This will invalidate the second Admin that was installed.