Updating contacts

We imported a CSV list from our customer data file (FM) and used it and accumulated info. and updated our customer file.
Q: If we import a new list that has same contacts and new ones will we lose stats accumulated for the existing? assuming it is the same email address?

It will create new CMS items (duplicates) and not replace or update existing ones. Can’t you filter out the existing records from your CSV prior to import?

As far as I know the import feature only creates new records, it doesn’t either update existing ones or check for existing duplicates to propose an action.