That isn't expected behavior. I expect it to target and clear the old install first and then install the update, for that is the expected behavior with the Adobe products.
If that Software Update was listed in the Windows Compliance by Bulletin Report as Vulnerable, and you created the Software Update Policy to deploy the update, and the Exit Code is 1611 outlined as
ERROR_INDEX_ABSENT 1611 Component qualifier not present.
This is found on http://support.microsoft.com/kb/290158
If you are utilizing only Patch Management to run the install as outlined on KM: HOWTO56242 (basic configuration of Patch Management); I feel a Support Case would be best to have this reviewed.
I am uncertain if this is a one-off anomaly caused by previous software deployment corruption, and that interfere with the Patch Assessment Scan targeting appropriately, but a Support Case with the Client Data found on KM: HOWTO60789 would be ideal to begin troubleshooting. The Support Team will see if it is reproducable and troubleshoot further.