Quote Originally Posted by Sheiky
Haven't seen the 2 copy-thing.

On the ISO 12233 charts, look for a pop-up menu next to the camera choice (or non-choice, if the lens was only tested on one body it's grayed out). In this example comparison (EF 70-200mm f/2.8L IS II vs. Tamron 70-200mm f/2.8), you'll see that the Canon lens has 3 tested copies, and the Tamron has 2 copies. I have to say - the Tamron does have impressive center sharpness!