How to convert stereo audio to mono
Many contesters record  SO2R audio as a stereo file. This can frequently be difficult to listen to after the contest.
The following is a simple method of splitting the stereo file into two mono files representing each radio.
1.  Download SOX  from here
2.  Install
3.  Use the command line interface to enter the following command
sox  stereoFile.mp3  -c 1  leftRadio.mp3 mixer -l
sox stereoFile.mp3 -c 1 rightRadio.mp3 mixer -r

For more details on other commands look here