Has anyone noticed before that when you run df on a union-mounted directory,
in which both the mounted directory and mount point are the same, the
results are all double what the filesystem actually has?  Is there a reason
for this?

It might make sense to add the source and target filesystem stats together
if they are different filesystems, _maybe_, but not if they are the same
filesystem or one is read-only (which I suspect would cover the majority of
union mounts).
-----------------------
Trevin Beattie          "Do not meddle in the affairs of wizards,
trevin@xmission.com     for you are crunchy and good with ketchup."
      {:->                                     --unknown