What is an 'overlay' data quality issue in a client registry?

An 'overlay' data quality issue in a client registry occurs when two distinct individuals are assigned the same identifier, leading to confusion and potential inaccuracies in data management. This particular situation arises when the information for two different persons is incorrectly combined, which can result in a mix-up of their records.

By having two people share one identifier, it becomes challenging to maintain the integrity and accuracy of the data associated with those individuals. This issue can lead to significant errors in patient care, reporting, and data retrieval in healthcare settings. Ensuring unique identifiers for each individual is critical in client registries to facilitate correct identification, reduce duplication, and enhance overall data quality.

The other options describe situations related to identifiers but do not specifically pertain to the concept of 'overlay.' Thus, they do not fit the definition of an overlay data quality issue.