Apparently there were two separate auditors to check the drawings — Smartplay International Inc. and Gaming Laboratories Inc., both of which are based in New Jersey (hmmmm....). (Documented here: http://www.lotterypost.com/news/161364)
The type of auditor you are referring to, like KPMG, audit the financial side of things, like jackpots, other prizes, distribution of funds, balance sheet, etc. The gaming auditors above are supposed to be able to determine if a drawing machine is operating properly.
Ultimately though, it is the Tennessee Lottery that is at fault. They are supposed to be the experts at their games. You can outsource the drawings, but you don't outsource your brain.
After a few drawings of no doubles they should have been more inquisitive. I'll bet they didn't bother to even look at the numbers themselves until players brought it to their attention. Then, I personally believe they told a tall tale when they told players that their people ran some sample drawings and saw doubles drawn. How could they possibly have done that? Why isn't the media reporting that??
This is very upsetting, because it is completely unnessesary. Why the h*** did they switch the drawings in the first place? They wrecked their relatively new lottery, as far as I'm concerned. Not only are the drawings fake now, but their credibility is destroyed.