Description of problem:
When the systems have the same hostname, only the last one can be kept registered in satellite6.2.

Version-Release number of selected component (if applicable):
Satellite-6.2.0-RHEL-7-20160907.6

How reproducible:
always

Steps to Reproduce:
1. Install 2 systems: RHEL-7.3-Snapshot-4.0-server-x86_64.
2. Make sure the 2 systems have the same hostname 'test'.
3. Register system 1 to Satellite-6.2.0-RHEL-7-20160907.6, and the system is recorded in satellite UI. (Please see attachment 'register_client1_successfully.png')
4. Register system 2 to Satellite-6.2.0-RHEL-7-20160907.6, and check the 2 records in satellite UI: the system 2 is recorded while the record of system 1 is missing. (Please see attachment 'register_client2_successfully_with_client1_missing_in_satellite_UI.png')

5. Check the identity of system 1 in CLI:
[root@test ~]# subscription-manager identity
Unit c1666704-99a2-4fc1-b9e7-70b87810aeb3 has been deleted

Actual results:
As step 4 and step 5..

Expected results:
All the systems can be registered with the same hostname. And all the systems should be recorded in satellite UI.

Additional info:
foreman-debug log is the attachment 'task-export-1474263771.tar.gz'