Rear fog lights

[Theiceman]

Hi guys
3rd Audi. Previous ones had rear drivers only.
My a4b7 has an error right rear fog light out. Huh ?? So I go check. And notice when you put rear fogs on both light up for a second then one goes out and I get the error.
So I swap the bulbs. And now the other side does it. So....,,

1. Does the b7 have two rear fogs
2. Does it only give an error because it sees it then it goes out ?
3. I noticed rear fogs are two different sizes. One looks like a regular tail light bulb silver base. The other looks like a short stubby bulb with a much smaller glass bulb with a silver base. Is one of them wrong ?

Many thanks as always.

[Theiceman]

Additional info

Thinking that maybe it was because it saw the light then it went out I removed that bulb, so it only had a bulb in the drivers side. Same thing " right rear fog light out" . The owners manual states there is only a drivers side fog light. So now I am thinking maybe someone went in and turned on the second fog light option through VCDS ( europen config ) any thoughts ? , for now im juat gonna get another 21w bulb and slap it in the other side to keep the warning light off.

[a4audi4fun]

FWIW - my Canadian B7 Avant has 2 rear foglights - the bulbs used are the ones that are on the hatch portion.

[Theiceman]

Thanks , I went to CT and picked up a couple of 21w bulbs, popped one in the right side and all is solved.