mergerepo weird behavior

Hello,

I'm seeing some weird mergerepo behavior I can't make sense of.  I have 
three repositories, PRODA, PRODB, PRODC, and each has a single package 
within it.  I'm trying to merge various combinations of these together.  
The example below tries to merge PRODB and PRODC into PROD-BC.


#mergerepo --repo=file:///<path-to-repo>/PRODB 
--repo=file:///<path-to-repo>/PRODC -o PROD-BC
Loaded plugins: refresh-packagekit
Not using downloaded repomd.xml because it is older than what we have:
   Current   : Tue Aug  9 09:36:40 2011
   Downloaded: Mon Aug  8 17:50:36 2011
3/3 - hp-PRODC-1.0-1.x86_64
Saving Primary metadata
Saving file lists metadata
Saving other metadata

The "current" timestamp of Aug 9 9:36 corresponds to PRODA.
The "downloaded" timestamp of Aug 8 17:50 corresponds to PRODB.
Though not listed, PRODC repomd.xml has a timestamp of Aug 8 17:54.

The result is that I end up with a merge of PRODA and PRODC even though 
I asked for PRODB and PRODC.

Here is the merged group file.
#cat groups.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE comps PUBLIC "-//Red Hat, Inc.//DTD Comps info//EN" "comps.dtd">
<comps>

<group>
<id>PRODA</id>
<default>true</default>
<uservisible>true</uservisible>
<display_order>1024</display_order>
<name>PROD-A Test Group</name>
<description>This is PROD-A #1111.</description>
<packagelist>
<packagereq type="default">PRODA</packagereq>
</packagelist>
</group>
<group>
<id>PRODC</id>
<default>true</default>
<uservisible>true</uservisible>
<display_order>1024</display_order>
<name>PROD-C Test Group</name>
<description>This is PROD-C #1111.</description>
<packagelist>
<packagereq type="default">PRODC</packagereq>
</packagelist>
</group>
<category>
<id>producta</id>
<display_order>10</display_order>
<name>Product-A Test Software</name>
<description>Product-A Test Software - Hello </description>
<grouplist>
<groupid>PRODA</groupid>
</grouplist>
</category>

<category>
<id>productc</id>
<display_order>10</display_order>
<name>Product-C Test Software</name>
<description>Product-C Test Software - Hello</description>
<grouplist>
<groupid>PRODC</groupid>
</grouplist>
</category>

</comps>


What am I doing wrong, or what have I set up wrong with my repositories?
Jon