Here are the links to the pre sale press releases, forwarded by The Philatelic Database before the 2011 sale and shared by Spink before the 2016 sale.
I introduced this lot as follows before the 2011 sale :
The first set of stamps for Hong Kong included seven denominations from 2 to 96 cents. It was issued in 1862.
The highest value was not widely used, and they waited until 1864 before reprinting. When the stock from the previous batch was depleted, it was discovered that the new batch of 52 sheets of 240 stamps had a nice olive-bistre color instead of the brownish gray that was required.
It was a mistake made by the subcontractor, linked to the fact that the wrong ink was part of the original color test.
The administration took the pragmatic decision to release it as is for delivery to the users during the few months which were needed to prepare a compliant printing.
The rarity of the Hong Kong 96c olive-bistre stamp is so due altogether to its high denomination and to the hurry to supersede it with stamps in the original color.
A single unused multiple is known. It is a block of four in great condition, with a very wide right margin. It has retained its original gum and its color is still very fresh.