[V8] interior light question

[UR32VQUATTRO]

Noticed something odd today while under the dash this weekend. My replacement v8q (build date 03/90) has a single bulb light on the driver side floor. now I mention the build date because my older pearl v8q( build date 06/89) has the two bulb setup (one red and the other white) The red one stays on during night time driving. My question is a two part question. Was this an option? If not, why would Audi revert back to the old style. Plug connectors are different. The one with the two bulbs has four wires and the one with the single bulb has only two. Just curious. Thank Allan