3738633 - Why do I see AD and ADBuyer prefixed addresses in my address export?

I see address entries with unique names prefixed with ADBuyer or AD in exported addresses or on documents. Some entries appear as near-duplicates that differ only by one digit (for example, ADBuyer[ID] and ADBuyer[ID+1]).

address unique name, cxml shipto, address export, sequential address id, address cleanup, shipto validation, invoice address creation, external shipto, adapter source null, address prefix, adbuyer prefix, legacy address, plant not acceptable, invalid shipto, procure adhoc address , KBA , BNS-ARI-CP-CORE-ADD , Core Administration Addresses , BNS-ARI-CP-CORE-IEX , Core Administration Import/Export , Problem