During the normal (classic) Excel Import and Excel Update Process we can select in the last windows if Duplicates should be allowed or no. So we can say no, through this all data will be updated as we want.

When we choose the Excel Online feature to mass update our data, this function is missing. so some records which have a potential record in the system will not be updated.

Could be please add this feature we have for excel offline import also for excel online import.