I noticed that pkg_add didn't check conficts that are registered from 
other packages. But only checks if the package to-be-installed has pkgcfl 
(CONFLICTS).

But when installing it does complain:
  Overwriting %s - pkg %s bogus/conflicting?

It may be useful to check the installed +CONTENTS files for matching 
pkgcfl -- but maybe that is too slow.

Or have the btree package database have that info.

Or have an option to fail before any installation or registration if file 
is seen already (instead of showing above warning).

Any thoughts about this?