Why do users sometimes receive messages repeatedly when I send text messages in groups?

It may be due to the following reasons

(1) If individual users repeatedly receive and there is no record of transmission, it means that the poor user signal at that time led to repeated transmission by the gateway. In this case, our company's SMS group software account will be deducted according to one SMS, and multiple SMS points will not be deducted.

(2) All or part of the users received repeated short messages, which can also be found in the sending records, indicating that the users accidentally clicked the send button repeatedly when the short messages were not sent, or the network where the users were located was unstable, resulting in repeated sending of short messages to the server for many times.