After installing a second multiplus 2 in parallel on my system, I encountered some problems. First, by connecting the two inverters via VE bus directly to Cerbo GX, the system goes into error. I therefore had to connect it via the MK3 to USB interface. Very strange, the inverters are working and powering the house and the exteriors but the Remote Console tells me that the inverter is off. Same thing on the VRM portal. 
@Giampaolo Did you just plug them together? Or did you set them up first the VE.Bus Quick configure tool?
Problem solved . I changed the UTP cable from multiplus to cerbo and all data are now available.
I have set the system with Quick configure to set the two inverter in parallel and then configured the two inverters.
And hopefully followed this: https://www.victronenergy.com/live/ve.bus:manual_parallel_and_three_phase_systems
Yes, I have read the manual and followed the Victron online courses. The two multipluses have approximately 10 weeks of difference and are updated to the 506 firmware. From this screen you can see that the system is working.
I'm going crazy with this . I cant solve the problem.Do you think may be usefull reprogram the unit again , I mean the parallel system?
