MailMerge.merge_duplicate_regions property. Gets or sets a value indicating whether all of the Document mail merge regions with the name of a data source should be merged while executing of a mail merge with regions against the data source or just the first one....merge_duplicate_regions ): doc = ExMailMerge . create_source_doc_merge_duplicate_regions...merge will affect both regions. doc . mail_merge . merge_duplicate_regions...