In the binary log we see that the disks from the original VM are backed up instead of the clone disks.
This can be identified by checking the datastore/path of the vddk files backups up and it can be seen that the path of the VDDK files is the path for the original VM and not the cloned VM.
This applies to VMs that are cloned without using the Clone Virtual Machine action in the vSphere Client, for example by cloning a datastore and adding the copy of the VM to the inventory.
In this situation vCenter might not detect that the uuid.bios value is conflicting with the original VM, and register the copy VM under the same uuid.
This will misleads the NetVault VMware Plugin, trying to backup the original VMs disks because the VM is registered with the same uuid.bios as the original VM.
The effect was that snapshots were created and deleted on the original VM, but the delta disks were remaining. This showed as "Consolidation Needed" on the original VM. Not dealing with this situation might eventually cause a large number of delta disks linked to the original VM, having severe impact on the performance.
Resolve the duplicate uuid.bios problem. See VMware KB below that explains what is required: