Good morning @2020ashish, Happy Friday! 
In Weaviate, each data object has two primary timestamps:
• creationTimeUnix: The timestamp when the object was initially created.
• lastUpdateTimeUnix: The timestamp of the object’s most recent update.
Both timestamps will remain identical until the object is explicitly updated using the update_object method, which only modifies the lastUpdateTimeUnix while keeping the creationTimeUnix intact.
However, in batch operations with add_object, if the same UUID is provided, Weaviate will overwrite the existing object, treating it as a new insertion. If the UUID is different, no overwriting occurs.
Does that make sense?