If you want the file to do almost the same thing, then why not just edit the file? Unless there is a compelling reason to keep the original file as it is, which is unlikely, then edit it to work the way you want.
The point we are trying to get across is: in order to demonstrate that you understood the original code base, you should edit it. If you delete a file and then add a new file that does the same thing (even if in a different way) I'll have to assume you could not get your head around the original file and therefore rewrote/replaced it.
It is important in a game development studio to be able to effectively read, understand and edit the code of your peers, spending time rewriting a class simply because it wasn't written the way you would have done it, is rarely acceptable. The time you spent doing this, could usually have been better spent elsewhere.