Can I transfer files between two remote servers with WinSCP

See documentation to learn how to duplicate files between sessions.

This feature is not build-in to WinSCP for reasons listed below. Yes there are ways to utilize some advanced features of WinSCP to achieve the task, see further.

• SFTP protocol does not allow this.
• With SCP protocol it may be theoretically possible. However it has many drawbacks. It would require not only major changes in WinSCP, but also many extensive configuration changes on both servers to allow authenticate on the second server from the first one (note that it would not be possible to use password authentication). So practically it would not have any advantage for most users.
• For FTP protocol has an FXP extension that allows this, but it is not supported by WinSCP. 309

With SFTP and SCP protocols, you can push the selected remote files to another server using scp custom command.

With SFTP and SCP protocols, you can use suitable remote command to download files to the remote server from another server. E.g.:

wget ftp://username:password@otherhost:/path/file ./