Re: WinSCP-5.12.2.RC-Automation Session.DuplicateFile
                You can use 
https://winscp.net/eng/docs/library_session_fileexists
https://winscp.net/eng/docs/library_session_removefiles
        Session.FileExists and Session.RemoveFiles to check for and delete any existing file.
https://winscp.net/eng/docs/library_session_fileexists
https://winscp.net/eng/docs/library_session_removefiles