[CentOS] YUM grabbing two architectures

Afternoon all,

Is there any particular reason why yum fetches rpms for two
architectures on almost any update/install I'd like to perform? This
includes both i386 and x86_64. Here's a small excerpt after performing a
'yum update'

 cups-libs               i386       1:1.1.22-0.rc1.9.18  update
   107 k
 cups-libs               x86_64     1:1.1.22-0.rc1.9.18  update
   112 k

I'm assuming I'll have to put in an explicit arch into /etc/yum.conf?

- sf