Duplicate PDFs created when using Windows Task Scheduler and auto-save feature

I have a batch file that prints a document to PDFCreator.
PDFCreator auto-saves it to a certain directory.
Windows 7 Task Scheduler fires this batch file daily at midnight.
When I fire the batch file directly, one file is created.
When I run the task, multiple copies are created.
Seems to be related to the number of users signed onto the computer. With one user logged on, two copies are created. With three logged on, four copies.
The task is set to run under the Administrators group. It doesn’t work when
set to run as a specified user whether the user is logged on or not

I installed PDFCreator as a service following these instructions:
http://rainyrat.wordpress.com/2010/01/22/pdfcreator-as-a-windows-service/

I also modified the registry so that PDFCreator’s auto-save settings
automatically apply to all users, including new user accounts:

[HKEY_USERS\.DEFAULT\Software\PDFCreator]

[HKEY_USERS\.DEFAULT\Software\PDFCreator\Program]
“AutosaveDirectory”="(path goes here)"
“AutosaveFilename”="(file name goes here)"
“AutosaveFormat”="0"
“AutosaveStartStandardProgram”="0"
“UseAutosave”="1"
“UseAutosaveDirectory”="1"

Any ideas? Do I need PDFCreator installed as a service at all?
This prints a document on the local computer and doesn’t rely on network resources.