Hi and welcome.
The schematics (click !) do not show separate pins, but also that the controller doesn't have 2 sets of I2C buses.
So the 2 I2C or 2wire connections are mirrors, connected to the same pins of the controller.
I2Cis a bus system.
It allows to have many (127) devices connected to it.
You need to address each device you'll be communicating with.
Lots of devices allow to set their address, within limits of course.
I see this Melexis device you'd like to use is factory set to 5A, but reading the datasheet there is some paragraph about how to set the address (im not sure i really understood it correctly).
If this proves to be impossible or too difficult to you, you could look into switching the I2C wires (using some kind of multiplexer).