So I backed into something and had to replace the rear drivers side taillight.
Ordered and installed the new housing successfully after transferring the LED matrix and turn signal bulb to it.
Tested it, everything worked fine.

Wanted to try LED 7440s, swapped out one for the bulb in the same taillight.
The thing went into hyperflash mode (I wasn't aware of the need for a resistor), so I swapped the bulb back in.

As I was re-testing for functionality (which was successful) I took my first real look at the bulb in the taillight and I found out that there seems to be TWO of them. It looks like two 7440 bulbs, one right above the other and both in the upper half of the taillight. (The LED matrix is in the bottom half.)

I thought maybe it was just the replacement housing, but it's on the passenger side as well, which came with the car when it was new.

All the instructions I've read, including the Honda repair manual for my car (07 4dr SE), only reference a single turn signal bulb.
And an accessible electrical socket has only been provided for one.

How do we change the lower of the two turn signal bulbs in the 07 Accord SE sedan?
(Owners of an 07 4dr SE - did you even know that the second bulb existed? If not go out and take a look.)

I'd be very curious as to what that second bulb is and how we're expected to change it in case (or when) it goes south.

Thanks in advance to all who might shed some light here (absolutely no pun intended).