Yes. DMS stores message replicas in multiple servers to achieve redundancy and high availability. In rare cases, a server storing message replicas may be unavailable when the client requests or deletes messages. If this happens, the message replicas will not be deleted from that server and may be sent when the connection is restored.
This process is called "at-least-once" delivery. To avoid any adverse impact from processing the same message multiple times, ensure that your application processes messages idempotently.