In recent modutils rpms, the new devel rpm has had a /usr/lib/libobj.a file in
it.  This file is the same as libmodutilobj.a, also provided in the devel rpm.

Fix:
Remove these two lines from the %install section of the spec file
install -m 644 obj/*.a $RPM_BUILD_ROOT/%{_libdir}
install -m 644 insmod/*.a $RPM_BUILD_ROOT/%{_libdir}

They are not needed as the following is in the %build section:
cp util/libutil.a libs/libmodutilutil.a
cp obj/libobj.a libs/libmodutilobj.a