Your sources don't know what they're talking about. Yours, or their, definition of overclocking is flawed.
Versions of that chip may not have been stable at 1.42GHz, and so were clocked at 1.25 or whatever.. but that doesn't mean a 1.42 was overclocked. Overclocking, by definition is done by the consumer and voids the warranty. What your arguing is incorrect.