From grahicssoft.about.com: "Copying and renaming a JPEG will not introduce any loss, but some image editors do recompress JPEGs when the Save As command is used. To avoid more loss you should duplicate and rename JPEGs in a file manager rather than using "Save As JPEG" in an editing program." Full article:
http://graphicssoft.about.com/od/for...mythsfacts.htm
HTH