If you encounter the following error when testing a Windows Server Cluster Disk;
Two disks have been found on node node1 that cannot be distinguished from one another. The disks involved have disk signature afac8423, SCSI page 83h VPD descriptor 60060160FB602D00E8C82BA2978CE211, SCSI page 80h VPD Serial Number CKM00112500835. Please verify the storage configuration. You must either mask (unpresent, detach) one of these LUNs at this node, or, run validation and specify a disk list that includes only one of these disks, for example by using the Test-Cluster cmdlet in Windows PowerShell.
The error probably relates to your MPIO configuration;
When you install MPIO you must configure it for iSCSI (if you are using iSCSI); so under Discover Multi-Paths tick “Add support for iSCSI devices” click Add and you will be prompted to Reboot.
After the Reboot you should now see the following iSCSI setting under MPIO devices.
Retest your cluster and hopefully the error will now be gone!