record or name on a list that matches one or more other records on the same list. Intra-list duplicates can occur when the addition of a new record to a file is made without an automatic or manual check for duplicates or when an entry or programming error changes the name and address elements of the record enough to bypass the dupe check system. Most list owners dedupe their lists periodically, if not continuously, using a computer program similar to that used in a merge/purge process. Every list owner or user has his own definition of a duplicate and therefore his own matching logic, based on the purpose of the list.
Intra-list duplicates can be a problem or an opportunity. They are a problem if the duplication results in customers' receiving and/or being billed twice for the same item or receiving duplicates of every promotion. They present an opportunity if customers who have made several different purchases can be identified for special promotions.
