Well, it's always good to have the photocopy of entire application package in the case if CIC says that you didn't submit a certain document. I have my complete application scanned including photographs and self addressed mailing labels. The date of scanned documents pdf file creation might or might not help you to fight with CIC if needed, in the case of them losing your document/s. At least I can check myself if I did a mistake or not, as my application package had over 1 kg of weight and it had over 180 pages.