items are pushed to queue in order, but applications polling or receiving records might get them not in the exact order ( Best-Effort Ordering) and occasionally a copy of the message could be delivered ( At-Least-Once delivery )

Standard queues let you have nearly an unlimited number of transactions per second. Standard queues guarantee that a message is delivered at least once. They also provide best-effort ordering which ensures that messages are gradually delivered in the same order as they are received.