Polyinstantiation is the ability of a database to maintain multiple records with the same key. It is used to prevent inference attacks.
Polyinstantiation (Wikipedia)
Polyinstantiation in computer science is the concept of type (class, database row or otherwise) being instantiated into multiple independent instances (objects, copies). It may also indicate, such as in the case of database polyinstantiation, that two different instances have the same name (identifier, primary key).
