Why does my mobile phone sometimes send two messages at a time?

I suggest you change your mobile phone to do a card test, that is, return your mobile phone card to a friend's mobile phone that can send text messages normally. So you can see whether there is a problem with the phone settings or the card. If someone else's mobile phone doesn't have this problem, it proves that there is something wrong with your own mobile phone. You should take it to the place where mobile phones are sold for inspection. If you put it on someone else's mobile phone and send it repeatedly, it proves to be a problem with your own card. Then dial 65433.