From what I can tell, google is either so short handed that they won't/can't look into these double/triple/quadruple serving cases unless the ads are selling/promting something illegal, OR they simply consider double-serving such a low priority that they only give each report a cursory glance. OR....[place tinfoil hat here] perhaps they use an internal ROI system to determine if is more profitable on a case by case basis to allow select advertisers to break the rules.
In my case, I first reported this months ago, and sent a PM to AWA with a very detailed report about with the URLs, the product, and even the name of the individual cheating the system. Again....nothing is done. As of right now (I wish I could post a few example keywords here) he has FOUR ads running for each KW in positions 1,3,7, & 8. Since he's been doing it for months, it MUST be profitable.
[edited by: WebFusion at 10:40 pm (utc) on May 14, 2007]