Notification Ring tone keeps repeating!? HELP

[AC Question]

Okay. So I have a galaxy s6 edge and lately my notification ring tone keeps repeating it self until I acknowledge it. This has been happening with my messages but not sure with any other apps. Is there and option for this in the setting or something for the notification ring tone to only sound once!??? How can i stop this??? It's really annoying and driving me a little crazy. Please help. It's the same if I put it on vibrate, it keeps vibrating repetitively. Thank you.