When running 'yum install' I see the following warning:
** Found 1 pre-existing rpmdb problem(s), 'yum check' output follows:
kernel-headers-3.14.4-200.fc20.x86_64 is a duplicate with kernel-headers-3.14.3-200.fc20.x86_64
This is the only affected package so I wonder if it's related to the custom handling of the kernel package.
I'm using PackageKit-0.9.2-3.fc20 from the GNOME 3.12 copr.
This might already be fixed by https://gitorious.org/packagekit/packagekit/commit/c3ddce1a4ec11884d57a10d023e8efd41fe7b2b4
Never mind, sorry, I misread the patch; thought it was asking hy what packages are installonly, but it was hif.
Anyway, I just tested this on rawhide and it seemed to work fine: updated kernel-headers and installed the rest of the kernel packages. Maybe some F20 quirk?
I helped recover a Fedora installation today that had duplicate packages due to https://lists.fedoraproject.org/pipermail/desktop/2014-May/009777.html . One of those duplicate packages was kernel-headers and for some reason 'package-cleanup --dupes' left that one duplicate behind after properly cleaning up all the others. I suspect this is also what caused your kernel-header duplicate and there's nothing more to fix here on the PK side.