What is the benefit of 2 drive thru lanes at a fast food restaurant?

The following photo shows the drive thru lane at a fast food restaurant. The lane splits in two to allow 2 drivers to place their order at the same time.

The following photo shows an overhead view of the restaurant:

As you can see, the two lanes converge back into one lane before the payment window. Therefore the payment and receipt of food is still done serially, which would seem to negate any benefit from orders being placed in parallel.

In addition, there are downsides to having more than one drive thru lane. A driver in one lane might not pay any attention to the other lane, which would increase the risk of an accident. Also, due to orders being placed simultaneously, the person at the payment window repeats the order to each driver to confirm that the orders/drivers are in sync. On more than one occasion I have had the wrong order repeated to me.

So what is the benefit of having two drive thru lanes?