Has it ever happened to you that you downloaded two files, which are supposed to be the same, they had the same size, but different name? If their size is equal, that doesn't mean the content is too. If you want to find out if they are the same or not this little app should prove useful over time.
In the app's window, you can drag and drop files into the two boxes, then click on the Compare button. If the file size is a match, it compares them byte by byte, then show the deviance in percents.