Assuming you now know how to do this, I would ask "why"?
What you are doing here seems like it could be dangerous to the security of your server, and at best, is likely to be unnecessary.
I suspect you are using an application that [wrongly] does a direct copy of an uploaded file to another directory? phpBB perhaps? If so, then there are other threads that describe how to deal with this.
No-one is going to stop you doing this, but I would recommend you seriously think it through. You may well be introducing a serious problem as a result of trying to work around a problem that could be solved other ways.
-- Jason