Six Sixes in an Over by Sir Gary Sobers

As i was surfing through for the match details found something interesting.It says,Malcolm Nash who bowled that fateful over used a sturridge ball to bowl to sobers,but at a recent auction in christie's they say it was a Duke and that it has been signed by sober's as well.Any idea what this is all about.
www.telegraph.co.uk/sport/cricket/103375...t-the-ball-used.html

Good observation BUT Garry did not really care about the Maker  ;D

                                       

If they don't care about the make it amounts to fraudulent activity right.Then you could probabably sue christie's for selling a duplicate product.
Moreover they can't go by what sober's says,he only "hit" the ball,and never handled it,so we need to go by what Nash says right..??
I am a bit confused over this and curious to know more.