This can be done by comparing the hash of the files. At this level you do not care about the type of content, but about the integrity of content. Basically, do this if you want to check if you exactly the same files.
md5sum audio1 audio2
2. Compare to see if the audio content is the same
This is not easy. You have to acoustically fingerprint the audio files and guess the kind of audio content they have. Only then can you compare these fingerprints (something like a hash, but derived from actual sound patterns). I am not aware of any simple tool for this, but Google may help to check out the more involved programs (music collection managers with fingerprinting support). If you do find a straightforward tool, let us know!