A couple of months back, I worked on setting up a SQL Server failover cluster for a customer. While preparing for installation, I ran the Windows cluster validation check and got the following error (obfuscating certain details):
Two disks have been found on node NODE that cannot be distinguished from one another. The disks involved have disk signature DISKSIGNATURE, SCSI page 83h VPD descriptor DESCRIPTOR, SCSI page 80h VPD Serial Number SERIALNUMBER. 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.
To resolve this error, my first step was to open the iSCSI Initiator tool in Windows. After going to the Favorite Targets tab, I noticed that two targets had the same name. Deleting one of those two targets resolved the issue and I was able to put together a SQL Server failover cluster successfully.