Slic3r Multi-extruder without GUI (no replies)

Hi all,

I'm trying to export G-Code for a 2 extruders .amf file with Slic3r using command line (without GUI). The .amf file has been generated before using Slic3r. I exported the Slic3r configuration for 2 extruders to a config_2extr.ini and I just execute the comand

>> slic3r.exe -load config_2extr.ini -o model.amf

I get the model.gcode and I can see that only use 1 extruder!!!

If I open the Slic3r GUI, load the config .ini file, a message box appears telling me that Slic3r is only able to import settings for the first defined filament (it not looks good...) and the combobox for the 2nd filament has no item selected. So I select the correct filament for the 2nd filament and generate G-Code, and this GUI generated G-Code is ready for 2 extruders!!!

So, my question is... is there any way to same the same with comands? why GUI is able to generate 2 filaments G-Code and comands no?

Sorry for my english...
Thanks :)