When a recurring all day event is created on the device and synchronized to the server, some of the instances look as if they are duplicated on the server. This was seen when using Outlook to view the appointment. 
This occurs only for the instances that have crossed the daylight-saving-time line.  These instances are one hour off, causing the instance to appear as if it begins on one day and ends on another - thus the instance appears on both days.

Example: An all day weekly recurring event created on February 2, 2009 and ending on March 30, 2009.
- Instances occurring before March 8, 2009 are correct.

- Instances occurring after March 8, 2009 are one hour off and appear on two consecutive days.