When I add an image with the file name "xxx multiple yyy.jpg" the HTML editor inserts src="xxx multiple="multiple" yyy.jpg" into the html code.
For an image at "http://xxx/moodle/file.php/6/WCM&AG/thumbnail/612%20CC%20multiple%20wdjt%20label.jpg"
e.g. <img title="612" height="200" alt="612" hspace="0" src="http://xxx/moodle/file.php/6/WCM&AG/thumbnail/612%20CC%20multiple=" width="390" border="0" label.JPG? wdjt multiple?>
I am using Moodle 1.6.6+.
Having identified the problem, I can work round it. I can't use a more recent Moodle as my ISP does not support Unicode.