Double notification for SMS

[hexa-db]

I'm not sure if this is normal behaviour or not but when I get an SMS, I get the normal notification & pings sound. If I don't read the message/clear the notification then I get repeat of it a short time later (maybe 30s - 1min or so).
This is currently on an XS Max with iOS 15.02 but it was the same on my older 6S as well.
I did wonder if it was something about my mobile provider but I have changed provider since.

Is this normal or am I special?

 

[now i see it]

Go to Settings > Notifications > Messages > set repeat alerts to never

 

[hexa-db]

Thanks! I had no idea that was an option