It’s time to test the double extruder for my BadPrinter2, but using pronterface I can only manage one extruder from the interface… Probably it is a silly question, but, how can I enable the second extruder in pronterface? Is there another printing software like pronterface as an alternative? (I’m using Marlin firmware)
Thank you
Try Repetier host it has support for dual extruders.
Cura has support as well , I believe.
Thank you, I wil try it, I already hear about that, but never tested because I’m quite fine with pronterface, but now I need this feature. Is it compatible with Marlin? Because I check now the website and I read about a Repetier Firmware, I need this or I can use my firmware?
Repetier is a fork of Merlin so yes it is compatible.
Cura works with Marlin 
@Stefano_Pavanello I’m running repetier host with marlin and its fine. All you need to do is set the serial baud rate. Pronterface feels very limited now after using repetier.
Just make sure you have your baud rate set correctly in Repetier as in your firm ware likely (25000) set your printer dimensions in the printer setup and setup slicer or forge. Load a model into Repetier and slice then print. Make sure you run through the setup in slicer and enable duel extruder support in the printer tab.
Thank you all again for the useful information, I think that I will happily spend my week end testing new printing software 
Actually we use pronterface because is the most straightforward and it works reliably, but compared with Cura (and I think repetier) seems, in fact, quite limited.
I like Cura a lot, and I’m very courious about Repetier, but at the first try we are stuck about the “baud rate problem” with Linux. Probably this is a little OT, but any help will be appreciated. We start testing with 115200 because we have and read some problem of Linux (Debian and Ubuntu) to manage the 250000 that is a non-standard baud rate. But with this low baud rate we have some printing problems, missing steps and so on, so we switch to the highest standard baud rate that is 230400 that works with pronterface, but I’m not able to make this work for Cura. It is my error or Cura does not support 230400 that is sound strange, but the auto detection fail to recognize my arduino, so, to speed up development time we continue with pronterface, but I think now it is time to explore new ways
The basic principle behind multiple extruders is that only one can be controlled at the same time (the other ones maintain their temperature, but are otherwise in standby). The active extruder is selected with the T command - T0 selects the first, T1 the second extruder and so on. Each G1 / M104 / M109 applies only to the extruder that is selected at that time.
Thank you @Thomas_Sanladerer now it’s more clear. If I understand well it is sufficient to me with pronterface to give direct command T0 or T1 and the interface reflect the selected extruder while the other remain in standby. I will try. Anyway from the suggestion of all of you now I’m very courious to test new softwares