What is reconciliation and safety data reconciliation in clinical data management?

What happens, once patient experiences any serious adverse event at investigational site then the investigator is suppose to fill SAE form and send it to the drug safety department of the company, and there the drug safety department will enter that SAE form in their safety database. At the same time investigator have to mention that serious adverse event in the CRF of that patient and then send it to the clinical data management dept. CDM role is to merge or reconciliate the safety database and clinical database of that particular patient in the oracle clinical dabase system.