Hello @Cheng Guan Chia ,
When a meeting is created, the organizer will send invitation to other attendees as well. You are getting a declined message back due to a conflict with an existing event in room resource calendar but the event is created in the organizer and other attendees calendar. This could be why you are receiving 'created' notification.
The meeting room is considered as attendees, and it is a default behavior that if one attendee declines the meeting it does not remove the organizer meeting request. The meeting is being declined and not cancelled therefore you are not getting 'deleted' notification.
Hope this helps.
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