OK here are the exact steps.
Use RecordPad V2.11 to create a stereo MP3
Save it to a file
Open the same file in WavePad V3.05
Crop unwanted start/end portions (at this point the file is in stereo)
Save the file
Re-Open the file in WavePad V3.05 and it now is in mono.
Why does this occur ?
What is the fix ?
Thanks