Fileplanet has a decent amount of sounds in
this package, everything in .WAV format. It's a mix of DN3D, Caribbean and MP sounds.
There's also
this (Duke Nukem 64 sounds, .WAV format) and
this (Balls of Steel, Duke: Caribbean, Duke Nukem: Manhattan Project and DN3D v0.99 Beta, mix of .WAV, .VOC and .OGG formats).