Save your original files somewhere and work with a copy. On the copy try deleting the noisy channel and the copy and paste the good channel into its place. Different software have different ways to do this. I know its real easy in Audacity.
You just split the stereo track into two mono tracks
then delete the bad one
then highlight the remaining track
go to edit and choose duplicate
then rejoin the two tracks into one "stereo" file
It will actually be mono since the exact same information will be coming out of both speakers. Like someone said, you can apply an artificial stereo effect but it would probably sound better without that processing.
I just tried it in Audacity to one of my recordings and it took less than a minute. If you don't like the results, blow it away and work on removing the noise in the original recording. For waht its worth, I always save my original files unedited and work with a copy. Who knows, in the future there may be some wonderful software that will make it perfect.