[CentOS] New rpm, same name, how to update

Mon Dec 8 16:34:44 UTC 2008
Robert Moskowitz <rgm at htt-consult.com>

I have to build my own rpms for the HIPL project.  I update my copy of 
the code and make rpm.

Thing is the rpm name never changes from patch to patch.

Is there a way to have yum apply the new code as an update and not have 
to erase then install?