double sms tone

[Tom112089]

hi. i am using chomp sms and have created a custom notification tone. the problem is my phone makes 2 sounds every time i receive a text, the default sound followed by my tone. i read to disable the sms sound in the stock message app and i did that but it still makes the double sound. any one know how to fix this?
thanks

Edit: forgot to mention im using 4.2.2 jellybean on the galaxy s4 sprint