Could be that Nikon cherry picks the sensors that perform the best (an old semiconductor trick to get top prices for the best performing microprocessors and then "binning" the lesser performing chips to a different price point.} Thus both sensors could come off the same line with the Nikons binned to the top, giving best performance, highest costs etc etc.
That is strictly a supposition on my part and not necessarily true. But it is an old model that may have been dusted off to separate performance between the two cameras. The performance benefit is real and whether it is worth the price difference is up to the consumer.