The percentage of names on a specific list that are simultaneously on another list. Its a calculation of affinity in the lists. Duplication factor may also refer to duplication among two or more indexes. If a rented index has a high dwelling index match rate, odds are that it is a fine index to popularize, when the duplicates are disposed of. The acceptance here is that crowd in the index contribute the same buying usages, and that once popularized, will gain clients.