[delphi.com.ar]

Prueba esto:

Código Delphi [-]
procedure TForm1.Button1Click(Sender: TObject);
var
  AStream: TMemoryStream;
begin
  AStream := TMemoryStream.Create;
  try
    RichEdit1.Lines.SaveToStream(AStream);
    AStream.Position := 0;
    RichEdit2.Lines.LoadFromStream(AStream);
  finally
    AStream.Free;
  end;
end;

Saludos!