I use the DISCO-L072CZ-LRWAN1 with the current configuration:
I2C1 ==> PB8 and PB9
I2S ==> PB13, PB12 and PB15.

And I want to use the other line I2C I2C2, but the I2C2_SCL is also on the PB13 (used by I2S).

There are other pins for I2C2?

Best regards.

look in the file bed-os/targets/TARGET_STM/TARGET_STM32L0/TARGET_STM32L072xZ/TARGET_DISCO_L072CZ_LRWAN1/PeripheralPins.c for PinMap_I2C_SDA and PinMap_I2C_SCL.
You will see all the options you have available and if pin already in use for other purpose.

Thank you