Why isn't cvstagdiff able to handle multiple modules?

[Vo, David \(Mission Systems\)]

According to the ANT documentation, it should be able to accept a space 
delimited list of modules but I have seen this is not the case.
 
 
Beginning of file ...
 
<property name="cvs.modules" value="Katepult Messaging Common Reusable Si3 Test 
UserDoc XML deployment ExampleAgent Specifications QATestAgent 
QARemoteTestAgent" />
 
...
 
 
  <echo message="Performing CVS Diff: ${cvslastgoodbuildtimestamp} to 
${cvstimestamp}" />
   <cvstagdiff
    cvsroot="${cvs.root}"   
    destfile="/home/builds/log/cvs_diff.xml"  
    package="${cvs.modules}"
    startDate="${cvslastgoodbuildtimestamp}"
    endDate="${cvstimestamp}"
   />
 
Sure enough, it diffs the entire list of modules, but when you look at the 
cvs_diff.xml file, it's usually void of entries. So I trimmed it down to one 
module. And it worked. Then I tried it with two files, with two seperate 
cvstagdiff entries. Guess what? It replaces the file each time. Why is this? 
Why bother allowing cvstagdiff the ability to diff multiple packages if it just 
replaces instead of appends?
 
Now my config is twice as large as it needs to be because it has to run a 
seperate cvstagdiff for each package and has to write to a dozen different 
files.
 
Any ideas around this?
 
Thanks,
David