I think I understand your problem now. If you were copying a fake
worm to a device of identical size, you could use copydev from h0, but
when copying a fake worm, you need to use copyworm from fh0 or
possibly even your normal main (c[w0w1]f{h0h2}).
check reports an fsize of 712733, so that's the highest block number
so far consumed by your fake worm, and is what copyworm should print
as your limit (plus or minus a few blocks) when you copy from fh0 or
your normal main. When you copied from h0, copyworm just used the
size of h0 as its upper limit.
Perhaps copyworm should complain if the source file system does not
contain a worm.
