It would replace it with the old cache file, although if the old one is simply deleted, it could probably be recovered with simple forensics tools. I've been able to recover deleted files with this: http://www.cgsecurity.org/wiki/PhotoRec Despite the name, it recovers many types of files. Of course LE would have better forensics tools than that. A more thorough way of doing what you are doing is to overwrite the entire hard drive with a tool like DBAN and then clone the backup onto the hard drive.