Hi,
The process will ingest all the records to data lake without any de-duplication.
Against the profile store, this depends on the type of schema you are using for ingesting data.
The Profile Record data any duplicate will replace the old record.(In the mentioned case, I am not sure which record will be picked by Profile store but there will just a single record)
For Experience Event, based on same_id profile store will reject the latest record from Profile Store.
Thanks!