Galaxy S3 2 notifications per text

[auctionsfromflorida]

When I first got the phone I was using default notifications, but then used Zedge to download a bunch of new ringtones and notifications. Since doing that, I set individual text and ringtones. However, when I get a text sometimes it: 1) plays the default and the new notification tone, one after the other. 2) and sometimes it plays the default rather than the new notification tone. How do I remedy this?