[Samba] fedora x86_64 packaging questions

[Mark Nienberg]

On a Fedora Core 4 x86_64 system the following packages are installed:
(These are the official Fedora packages, not the samba.org fedora packages)

samba.x86_64
samba-client.x86_64
samba-common.x86_64
samba-common.i386
samba-swat.x86_64

Note that for samba-common, both the x86_64 and the i386 packages are installed.

Questions:
Why does Fedora do this?
Is it really necessary?

I ask because I recently thought I would download the latest Fedora Core 5's src rpm 
and rebuild it on Fedora Core 4, but when I did it built all x86_64 rpms and did not 
build the i386 rpm.  I'm wondering if it matters.

Thanks,
Mark