I think I am very lucky to have this. I have never seen it anywhere else.
It has often crossed my mind whether it might have been produced just for me. I would doubt it, really, as it would have been a lot of trouble, but in places it certainly seems to have been done in a bit of hurry with quite a few "typographical errors" here and there - see the spelling mistake in Acorn's address here. This is quite a contrast with the actual letters which were always word perfect.