yum and multiple architectures... help!

Hi,

I've been trying to understand how yum is meant to work when a system supports multiple architectures.

My case is Fedora 8 on PS3, architectures ppc and ppc64.

Example 1 (gdb):

1) who owns /usr/bin/gdb

gdb,"6.6","Fedora Project","Development/Debuggers","GPL",ppc"
gdb,"6.6","Fedora Project","Development/Debuggers","GPL",ppc64"

2) which gdb is it?
[root@ps3 ~]# file $(which gdb)

3) how do I get gdb.ppc64?
The only way I've found is: remove both of them, reinstall gdb.ppc64. It does not look right to me!
It should at least complain!
They are not the same. gdb.ppc only debugs 32bit apps, while gdb.ppc64 works for 64bit apps!

I thought that there cannot be 2 packages providing the same file as in the following:

Example 2 (alsa-lib-devel):

1) which alsa-lib-devel do I have already?

alsa-lib-devel,"1.0.15","Fedora Project","Development/Libraries","LGPLv2+",ppc64"

2) let's add the ppc version

[root@ps3 ~]# yum install alsa-lib-devel.ppc
Setting up Install Process
Parsing package install arguments
Resolving Dependencies
--> Running transaction check
---> Package alsa-lib-devel.ppc 0:1.0.15-1.fc8 set to be updated
--> Finished Dependency Resolution

Dependencies Resolved

=============================================================================
 Package                 Arch       Version          Repository        Size
=============================================================================
Installing:
 alsa-lib-devel          ppc        1.0.15-1.fc8     fedora            989 k

Transaction Summary
=============================================================================
Install      1 Package(s)
Update       0 Package(s)
Remove       0 Package(s)

Total download size: 989 k
Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test


Transaction Check Error:

and so on for many other files.

How it is meant to be used?

Andrea