SEPM does not validate if GUP is online or offline, it gives out the list of GUPs to get the updates from, The clients will keep track of the interval ( Bypass) ..Liveupdate schedule is local to the box, these settings are set in the registry when it reaches the schedule it will run Liveupdate.
Just set one option which you are comfortable with , Symantec also does not recommend using too many liveupdate sources
Why dont you try this option, which is in the liveupdate schedule.
Options for Skipping LiveUpdate
Specifies that LiveUpdate should run automatically at the next scheduled time if the checked criterion is met. If you check both options, the client computer must meet both criteria for the scheduled LiveUpdate to run on schedule. If the client does not meet one condition, then the scheduled LiveUpdate is skipped and an entry is made in the client system log.
http://www.symantec.com/business/support/index?page=content&id=TECH178257