After some more investigation, it seemed like when printing a part with two materials, Cura will turn off the inactive nozzle after it finished all moves (M104 T1 S0). However, when using a second nozzle as support, Cura will set it to the standby temperature after it finished all moves instead of turning it off.
I know it is a huge achievement and no easy task to write Cura. I really appreciate any help.
Thanks