Below steps would give you a good idea
1. Keep uploading the file to a single server.
2. Create a FTP job and deploy it in the web server, where the files would be uploaded.
3. For creating an FTP job use .net windows service or a simple exe which has to be scheduled using windows task scheduler to run after a particular interval.
4. FTP job should keep polling the upload directory for files.
5. If any file is found, do an FTP send to a list of servers which you can maintain in your config file.
For information about performing FTP job in .net go http://www.csharptalk.com/2010/01/how-to-download-file-from-ftp-server-in.html.