bugfix: duplicate key-versions to same endpoints.

Change-Id: I918d5634ec0360e4de053668d5694a1c91e8c3cd
Reviewed-on: http://review.couchbase.org/43525
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>