AddSignUps add those PI Points to the Update Manager subscription on the PI Server.
The PI Update Manager will start queueing events for those points for your subscription.
(1st) GetUpdateEvents(10000) will retrieve the events for that queue up to a limit of 10000 events. Events are dequeued from your queue within the PI Update Manager.
(2nd) GetUpdateEvents(10000) will retrieve the events for that queue since the last GetUpdateEvents call.
Note, if you have more than 10000 events queued you probably want to empty the queue first before sleeping until your next call to GetUpdateEvents.
Rhys, Thank you very much