Safari :: How To Stop Renaming Download Files

If I download a hjsplit file (a file split into multiple, consecutive parts .001, .002, .003, etc for recombination by the hjsplit program) safari tries to be clever, and adds a file extension of the file type, so instead of getting 3 files called: 

x.001

x.002

x.003 

I get something like 

x.001.mp3

x.002.mp3

x.003.mp3 

Presumably the website tells safari the filetype, but usually a browser allows me to override mime types like this.  In firefox  files are not renamed (so I know it is theoretically possible), whereas in safai they are, and therefore are no use to the hjsplit program until I manually rename them. 

I think this is a webkit thing, since chrome does the same thing, whereas gecko browsers like firefox and camino do not. 

Info:
Mac Pro, Mac OS X (10.7)