Could rev 7 have been pre-jumpered to use 1MB Chip instead of 512K Chip / 512K Slow? I could imagine Commodore trying something like that and then pulling back.
It kinda reminds of the time they assigned an agnus chip the wrong number for the pin out they used.
It's commodore, they might have had an argument over what to call it and sent the wrong artwork.
The other option is slightly different for some part commodore thought they could get cheaper, then didn't.
