What is "Error: Protected multilib versions: ..."?

[Richard W.M. Jones]

I get this error all the time, but I can't find a coherent explanation
for what it means.

What is the precise meaning of the "protected multilib versions" error?

# yum install /lib/ld-linux.so.2
[...]
Error: Protected multilib versions: glibc-2.14.90-4.i686 != glibc-2.14.90-1.x86_64

# yum install /lib/ld-linux.so.2 glibc-2.14.90-4.x86_64
Loaded plugins: auto-update-debuginfo, presto, refresh-packagekit
Setting up Install Process
Package glibc-2.14.90-4.x86_64 already installed and latest version
Resolving Dependencies
--> Running transaction check
---> Package glibc.i686 0:2.14.90-4 will be installed
--> Processing Dependency: libfreebl3.so for package: glibc-2.14.90-4.i686
--> Processing Dependency: libfreebl3.so(NSSRAWHASH_3.12.3) for package:
glibc-2.14.90-4.i686
--> Running transaction check
---> Package nss-softokn-freebl.i686 0:3.12.10-4.fc16 will be installed
--> Finished Dependency Resolution
Error: Protected multilib versions: glibc-2.14.90-4.i686 != glibc-2.14.90-1.x86_64

# yum install glibc-2.14.90-4.x86_64
Loaded plugins: auto-update-debuginfo, presto, refresh-packagekit
Setting up Install Process
Package glibc-2.14.90-4.x86_64 already installed and latest version
Nothing to do

Bonus question.  How come rpm/yum has allowed me to install multiple
different versions of glibc?  (I have never knowingly forced any
installation on this machine).

# rpm -qa | grep glibc
glibc-utils-2.14.90-4.x86_64
glibc-2.14.90-1.x86_64
glibc-headers-2.14.90-4.x86_64
glibc-debuginfo-common-2.14.90-4.x86_64
glibc-2.14.90-4.x86_64
glibc-static-2.14.90-4.x86_64
glibc-debuginfo-2.14.90-4.x86_64
glibc-devel-2.14.90-4.x86_64
glibc-debuginfo-common-2.14-2.x86_64
glibc-common-2.14.90-4.x86_64
glibc-common-2.14.90-1.x86_64

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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[Sam Varshavchik]

Richard W.M. Jones writes:

>  glibc-common-2.14.90-4.x86_64
>  glibc-common-2.14.90-1.x86_64 
This means that rpm/yum aborted in a middle of a upgrade.

You should clean this up using rpm -e glibc-common-2.14.90-1.x86_64