Description of problem:
Adding queue/topic with 2 jndi entries which are the same should not be allowed. 

[standalone@localhost:9999 /] /subsystem=messaging/hornetq-server=default/jms-queue=testQueue:add(entries=["java:/jms/queue/testQueue","java:/jms/queue/testQueue"]
{"outcome" => "success"}

[standalone@localhost:9999 /] /subsystem=messaging/hornetq-server=default/jms-queue=testQueue:read-resource
{
    "outcome" => "success",
    "result" => {
        "durable" => true,
        "entries" => [
            "java:/jms/queue/testQueue",
            "java:/jms/queue/testQueue"
        ],
        "selector" => undefined
    }
}