Of course not. My boss wanted me to unlock something he got from his supplier so that he could show a customer, without showing the customer his prices. He would just duplicate the spreadsheet, but there are pictures stored in the comments that cannot be copied with the protection on.
I've done this once before with a little add-on program for excel, but I don't remember what forum or which user I found it through. There used to be someone with a link in his signature for it, but I haven't been able to find it.