Not sure if it has to do with Daylight savings time or not. The weekend of the time change, Our backups began occurring twice. We have a small amount of data that takes 56min to back up. (13 Gig or so) (Windows 2000 server fully patched.) We schedule it for 10PM and no later than 10:59PM. Back up happens at 10 and then again at 11PM.
The possiblilty exists that the back ups used to be scheduled for 11. (Perhaps something buried in the registry triggering this...??)
I have already looked at the following link: http://seer.support.veritas.com/docs/233078.htm This article refers to the older version of BUE. This check box does not exist in 9.1
I have adjusted the time window to 10PM no later than 11:55PM to see what happens.