i doubt any developer will add anything to their client to specificly aid in your warez needs.

i doubt any developer will add this feature becuase it's need is very specific. much easier for you to share differnt dirs.

your thinking if flawed becuase you think that everybody have exactly same mp3 as you do. search for something very common like "metallica" and you'll get a few thousand results, look at most common file, you'll get about 50 hosts with EXACTLY same file, which is very little for this number of hits.
you think hash will help? but consider this. if you change your ID3 tag, file hash will change, even if song is encoded exactly same way.


in conclusion, your idea is stupid. if you afraid to get busted for spreading warez(mp3), don't do it. if you are too lazy to rename dirs, don't share illigal files. i hope developers won't waste time adding your feature request.

have a nice day.