Mac OS X Server v10.5.8: Invalid serial number after updating
Mac OS X Server 10.5
After installing Mac OS X Server v10.5.8, Server Admin may report a duplicate serial number in use on a server with multiple network interfaces.
If you have already installed Mac OS X Server v10.5.8, manually download and install the Mac OS X Server v10.5.8 Update v1.1 from Apple Support Downloads.
If you have not yet updated from Mac OS X Server v10.5 through v10.5.7, you can avoid this issue by installing the Mac OS X Server 10.5.8 Update v1.1, which is available as an automatic Software Update, and as a manual download from Apple Support Downloads.