I would suggest to take one of the sound legs and edit in WavePad....use the amplify or soften feature, (hot tab on your left) and make it as loud or as soft as the other recording....then highlight the whole thing, and use the 'remove hiss and noise' feature, also on your left.
Remember, the more positive you go towards '0' the more you will make it silent...I would suggest going '-36 to -20'...going negative will allow the sound to come through and the hiss to disappear.
Remember to make which ever the dominant one so that you can set your standard to that one...If you have MixPad, you will be able to put both recordings down and have them play at the same time to determine if you set your levels correctly. You can also do it on WavePad, but I just like using MixPad to hear the finished corrections.
Make sure to make copies of the original file first while you experiment with the sound corrections...
THEN GO TO OPTIONS>GENERAL>USE DEFAULT SAMPLE RATE AND CHANNELS>SET DEFAULT(LARGE LONG BAR)>MONO>>>SAVE AS
Hope this helps,
JG