I sent a message. . Others received three identical messages.

It's a problem with the mobile or Unicom service center. You sent one. You only charge for text messages.

After receiving and transmitting by satellite, the other party will send a feedback signal. After the satellite receives and reconfirms, the short message is sent successfully.

If there is feedback delay or the signal is busy, the satellite can't receive the feedback from the other side in time, so it will keep sending information until the feedback from the other side reaches the satellite, so that the other side will receive multiple identical messages.

There is such a thing in life, I have seen the news, that person will receive the same content information every 2 minutes, and his job in a day is to delete these information constantly.