Description of problem:
When user tries to assigns duplicate MAC address to NIC, Following error message appears:

Mac Address is already in use.

MAC should be in capital letter so it matches with the rest of rhevm environment (see screenshot, there is 3 occurrence of MAC) 


Version-Release number of selected component (if applicable):
oVirt Enterprise Virtualization Engine Manager Version: 3.1.0_0001-9.el6ev 

How reproducible:


Steps to Reproduce:
1. Assign NIC to VM with custom MAC address
2. Try to assign second NIC with same NIC to the VM
  
Actual results:
Mac Address is already in use.

Expected results:
MAC Address is already in use.

Additional info:
This case assumes that AllowDuplicateMacAddresses=false in rhevm database