[LAU] Audacity strange behavior

[Folderol]

As a double blind test when seeing what changes were made to Wav files
when translating to and from Flac, I also used Audacity to make a
direct copy using 'Export'.

To my surprise, the copy had a different md5sum signature.

Thinking that the export operation might be creating the differences I
exported another copy, but this turned out to have a different
signature to both the previous ones. A third copy was again different
to all the others.

Listening to the files I could detect no difference, nor could i see
any difference in Audacity, even when stretching the display enough to
see the actual waveforms.

It occurred to me that the differences might be due to some sort of
timestamp embedded into the file header (I don't really know what
meta-data Wav files contain) so I looked at the files in a Hex editor,
cecking at several identical locations through the files. They all
showed up as different, and it wasn't just the same pattern but shifted
a few bytes.

Can anyone suggest what might be happening here?

-- 
Will J Godfrey
http://www.musically.me.uk