How to prevent AudioSource distortion?

When I have multiple AudioSources playing the same clip, I notice that the sources stack one over the other and increase the volume causing some weird distortion. Also, I am using the Spatial Blend on the 3D setting to make the user hear the sound at he is closer to the audio source (in this game, as the character moves closer to the torch, he would hear the fire sound louder). Please let me know how can I fix the audio sources stacking, and how to avoid the corruption/distortion.