Adding VNX LUNS to ESX

I'm trying to add 4 VNX LUNS to our production ESX 4.0\ESXi 5 VMware environment.  Each LUN is 1024 GB - we want two 2 TB VMFS3 datastores.  In vCenter I created the first 1024 GB datastore.  When

trying to add an extent for the 2nd 1024 GB LUN I noticed that the LUN # displaying in vCenter was not the same as what the VNX shows.  I issued a couple of rescan all commands, but still see the same

difference in LUN numbering.  Is this normal - should I be concerned ?  Thx.