This is a capability that could be addressed in a future version of the IG once we identify the type of requirements that we need to meet for de-duplication as it is very use case specific (e.g Healthcare Surveys may not be affected by duplicate data, however cancer registry reporting may be affected if duplicates are sent). Modification to RA IG: Add a note in the Data Receiver section as follows “Expectations of the Data Receiver with respect to duplicate data has to be specified in the Content IG and corresponding requirements have to be added to the HDEA in the Content IG”. E.g., In the Cancer use case, duplicate messages are not to be sent and an explicit requirement has been added to the Central Cancer Registry Reporting IG section 3.1.5.5.4: https://build.fhir.org/ig/HL7/fhir-central-cancer-registry-reporting-ig/spec.html#knowledge-artifact-processing-requirements