rpm file conflict detection - how to reenable?

[Robin Green]

In FC4test1, rpm does not error out on file conflicts.

(Example: libswt3-gtk2-3.1.0_fc-0.M5.12 from fc4test1 and rssowl-1.0.2-0.2
from
http://prdownloads.sourceforge.net/rssowl/rssowl_linux-1.0.2-0.2.i586.rpm?download
both contain some files in common, e.g. /usr/lib/libswt-atk-gtk-3123.so,
but rpm does not complain when you install rssowl when libswt3-gtk2 is
already installed.)

How can I reenable the old behaviour?

Thanks
-- 
Robin