I just unbranded mine and enabled Dual SIM.
I have to say it is not free... but the seller support is really great.
So from a bricked one (see my other topic) I revived it with DC Phoenix.
and then with DC-Unlocker seller'ss help, with HCU Client + DC Phoenix we succeeded to flash unbranded C432B105 ROM, and then enable the second SIM slot.
DC Phoenix is for flashing ROMs from DC-Unlocker's support area.
HCU Client is for changing values like Vendor, Country, Model...
I can't be very specific about the exact procedure (I'll let you guess why...) but the things I can tell :
1/ Flashed Warsaw-L01_C432B105_Firmware_United Kingdom_Nonspecific_Android7.0_EMUI5.1.APP with DC Phoenix (Fastboot mode and then Upgrade mode)
2/ Flashed Warsaw-L21A_C432B105_update_data_customization_hw_eu.APP with DC Phoenix (Upgrade mode only, no need for fastboot mode)
3/ Changed some values with HCU Client like :
- Model name : WAS-L01A -> WAS-L21A (not sure it was really usefull, a guess from P10 with its VTR-L09 and VTR-L29)
- Vendor : orange (default phone value from my carrier) -> hw (need to fit the custom APP flashed in step 2)
- Country : all (default phone value from my carrier) -> eu (need to fit the custom APP flashed in step 2)
- SIM card mode : Dual SIM (was already set to dual but forced it again, not sure it was usefull)
- ... (you'll have to guess what and why you have to guess it...)
You'll need 15 credits for DC Phoenix and 8 credits for HCU client... you can think it is expensive, but yesterday my phone was bricked, so his help and support saved my phone, and my day!
Don't ask me to upload my OEMinfo partition as I won't unlock again my bootloader (the crappy message at boot is just not for me...), I won't flash TWRP.
It is not a hidden promotion message, it is just to tell there is an alternative solution to unbrand it and add Dual SIM support.