There's no scripting command for this operation.
Anyway, when you use Duplicate command in GUI, all it does (with SCP/SFTP) is that if executes "cp" command on the remote side.
You can simulate that with "call" command:
call cp /source /target
With FTP this is not possible (neither in GUI).

Hello,

I'm newbie with WinScp Scripting.

I would like copies files between two folders on a same server.

Like this "COPY" /source /target

Is it possible?

Thanks!

Duff