Scenarios Deduplication

Hello Dear,

I have some questions:

My file server is Windows server 2008 R2;
My backup server is in Windows Server 2008 R2;
Use backup server in the Windows robocopy to bring information from File Server and then save LTO tape with Arcserve Backup.

If I upgrade the server to Windows Server Backup 2012 and deploy Deduplication, the night when the robocopy performs incremental backup of files to the File Server Backup Server, I have problems with deduplication?

Files copied to the backup server will return to normal size? or have the size as the deduplication configured?

What better scenario in my case? install windows server 2012 on fle server and enable deduplication?

Thank you.