Neat! But why didn't they go the whole hog and make them 6.5? Latest & greatest, and all that...
My guess is it's the 6.2 fixes that "mattered" and so they sensibly decided to incorporate up to that level on the PCB.
Indeed, it seems:
6.3 boards just bring ECS Denise and KS 2.04
6.4 - 6.5 boards support the 8375 Vbb replacement Agnus for the older 8372A (they still got it wrong on 6.4 and had to rework, 6.5 was probably a correction to the "correction").
So 6.3 is a cosmetic and 6.4 - 6.5 an undesirable difference, as the vast majority of Agnii out there (either as working motherboard pulls or individually available chips) is the 8372A (318069-029) and not the Vbb 8375 1 MB replacement (318069-16/17).
Hence the 6.2 rework level.