Automatically Merging "Dual Mono" files to a Single Mono File?

[McLilith]

I have a fair amount of audio files in "stereo format" that I suspect are actually mono recordings. Is there any free and easy piece of software that will analyze a collection of audio files, figure out which of the "stereo files" contain no actual stereo content, and convert those files to single-channel mono audio files, which will take up half their original hard drive space?

I could do this manually, but it would take ages to sift through all my audio files. I'd like to automate the process as much as possible, if not completely.