FreeBSD : conflit de portmaster sur un nom de package

===>  Installing for pkgconf-0.8.9

===>  pkgconf-0.8.9 conflicts with installed package(s):
      pkg-config-0.25_1

      They install files into the same place.
      Please remove them first with pkg_delete(1).
*** Error code 1

root@box15:~ # portmaster -o devel/pkgconf devel/pkg-config