Keywords: Address quality, Data quality, Addresses, Address database, CRM, Duplicates, Duplicate check, De-duplication, Software.


Duplicate addresses are one of the major nuisances while dealing with addresses – from simple customer mailing up to address database in the CRM-, Marketing- or ERP-System.

Duplicates always originate in the same way:

  • If a person, company or institution that has already been saved is not noticed while creating a new address. This can remain undetected for many reasons: Writing-, listening-, reading- and other errors, write-variants (primarily in companies), change of name (e.g. after marriage) or the address (e.g. after relocation), changed postal code, city-or street names (e.g. after incorporations).
  • A special “profitable” source for causing duplicates is if addresses are managed in several inventories, which should then be merged for introducing a new software solution. Often departments or employees begin to collect addresses in Excel-Tables or small Access-applications besides the central address database, because it is initially easier.
  • Purchase and/or leasing of external address lists, e.g. for sales campaigns, can regularly cause new duplicates. If address lists for the same target groups are used, it would be a cause of worry if there would be no overlapping.


De-duplication is more complicated than correcting wrong salutatory addresses and addresses:

  • While checking salutatory addresses and addresses an individual address will be checked against an external reference inventory and if necessary corrected. Generally other data records are not affected by the change.
  • During a duplicate check each individual address is matched with all the remaining addresses. If a duplicate is found, then the aim is to eliminate it. But, often further information is included in this duplicate address like orders, invoices or marketing information.
Usually duplicates are not as charming as these two ladies.

Thereby q.address proceeds variably depending on the task: In case of a duplicate check and cleansing of entire address files or address tables within databases an address is not compared one by one against the entire inventory, but there are much more efficient procedures. However, in case of an interactive check, i.e. in case of an interactive new creation or change of individual addresses there is no other option. q.address offers various solutions.

For further reference, please read:

  • for de-duplication in address files or database tables:  here…
  • for interactive duplicate check in address databases:  here…

Further links