The new ratings released after October Challenge have seemingly changed the ratings of the previous challenges in some user profiles. The ratings that went up after September challenge and were expected to go further up after October Challenge now show to have went down after September Challenge. In short, the October ratings have also changed the September rating in a few profiles like:
http://www.codechef.com/users/pranav9413
http://www.codechef.com/users/coolbun
please look into the matter… 
Yes, it is correct. according to the new system to combat cheating, each time the ratings of a contest is calculated, the cases of cheating in the previous contest are also considered so ratings of both contests are re-calculated. This is done to reduce time taken to calculate new ratings as it takes time to report all the cheating cases of the previous month. In short cheating cases of October will be considered while calculating ratings for November and first October will be recalculated considering cheating and then November will be calculated without cheating.
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