Lun mapping - duplicate LUNid in ESXi

Hi

We have NetApp array presenting iSCSI  to ESXi 5.0u1 servers.

I am trying to see if I can identify iSCSI devices presented to ESXi server  as LUNs created on NetApp. Until now I was under impression that this mapping should be one to one for our setup but this does not seem to be a case:

This is what I see in devices list on ESXi server. As you can see, the LUNid is the same, but size is different.

From NetApp array, only one LUN (with Size 64 GB)  with LUN ID 4 is presented. First Initiator Group is not used.

Does it mean that ESXi server LUNID mapping is out of sync with NetApp array?

How would I be able to identify LUNs then - I thought that LUNid would be a unique identifier but now I am at loss.

Thank you!