The phone always automatically displays "Message sent successfully!", what's going on?

Are these two phones the same phone?

If it is the same mobile phone, it is possible that there is hidden software in your mobile phone that will send text messages to confirm the information, or charge a fee or something.

It is best to quickly check where the text messages are sent, because some text messages are paid text messages, and sending one costs 1 yuan or 2 yuan.