Why does my iPhone 5s vibrate once and then 2 minutes later again?

So everytime I receive a text when I'm not on my phone, it vibrates once notifying me and then 2 minutes later it vibrates again. It sounds as if I got a new text but it's that same one like if it's reminding me. I really don't like this, my 4s didn't do that so does anyone know if I'm able to change this? I just got my iPhone 5s like literally 3 days ago, so it's like brand new.

Mine does this also. Have you tried changing the settings?

Go to settings and find notifications, then scroll down to messages, them scroll down a bit to repeat, change that to "only once"

Every iPhone by default repeats message alerts so you don't miss them. If you don't like it, you can change it in settings. Go to Settings -> Notification center -> Messages and change Repeat Alerts to Never