There is some info here...
http://forum.a8parts.co.uk/showthrea...35225AK&page=2
You could also look on here...detail and cross reference all the PR codes on a VAG decoder website...
https://audi.7zap.com/en/rdw/audi+a8.../a8q/2006-291/
I think one is for the rear window without the heated element lines, instead it has the blue/purple metallic vapour coating you used to see on French car windscreens in the early 00's.