When it comes to discharging batteries, getting the discharge rate and end point voltage correct can make a big difference to mAh reading. Not all manufacturers use the same parameters, and often as not, the ones camera manufacturers use to rate the "number of clicks" they advertise for the body will reflect average or light battery use operating, it won't necessarily be under the most battery intensive operating conditions so any quoted values should be taken with a pinch of salt. Also trying to exactly replicate these figures should be taken in a similar manner as you can't replicate the unknown.