Purposes of two separate wires at Front Door Switches?

After careful studying of the door lock system of i20 2011 with the wiring diagram, it is observed that -
All red wires go to one BCM connector, and acts as a sensor for the following conditions:

Now, with all 4 doors remained closed and keeping them unlocked.
1. If anyone or all of the 4 doors is/are opened, the BCM signal changes to 0V from 12V. When trying to lock the door, the central lock function will not work.

2. With the center lamp switch set to door, if anyone/all doors are opened, the BCM signal changes to 0V again, and hence, the center room lamp will light up.
Both of the above 2 conditions are normal.

However, there are another 2 separate wires marked purple which goes into the BCM again.
One wire for the driver side switch, and another wire for the passenger side switch.

Now, I wonder what these 2 extra wires are really meant for. What are their purposes/functions?
In fact, all required locking features/room lamp system are already executed using the red wires as mentioned previously in the above 2 conditions.
I'm really curious what are the 2 extra signal wires for?