Having been trying to get to the bottom of this for a couple of days, I received this message from someone who is well placed to know.
Hi, thank you for your reply. Whilst we are unable to 100% confirm the authenticity of the burrs. It seems to be original and the packaging and part number listed on the box correct. It is possible Eureka uses multiple manufacturers for their burrs. From experience quality can differ a little from batch to batch especially on the lower end burrs.
The wording stamped on the burrs from the picture you sent stand for as follows:
MAC stands for Macine. Translated from Italian is Millstones ie. Grinding Burrs.
75, Is the diameter of the burrs 75mm.
ITA stands for Italy.
TI stands for Titanium
Generally speaking the quality control is better on the VA / NS then on the Eureka versions of these burrs in terms of finish. But all versions will do the job just fine.
So I have contacted the Ebayer, apologised and am now quite happy (to a certain point!)