I think what he is trying to do is compare the CONTENTS of the file to see if they are the same. I believe he wants to make sure the contents are or not. Now, there used to be an old DOS based Norton program (Norton Utilities) that would compare the contents of a file (where you could split the screen and see the same file name say from two different drives in each side of the split screen and Norton would high light the same or additional content of that same file name) but WOW that was years ago since I've seen my copy even. My suggestion, since you can not compare the contents of the file in any Windows program that I know of, I would look at the file size and compare that to the file that you are trying to copy into the, I take it, the same folder. Hope I'm right in that assumption. If the file size is the exact same then, it would be prudent to assume that they have the same content. other than that... Your going to have to read the file manually and make the best guess as to weather they are the same or not.
All the best with that
God Bless
Doc