Identifying potential duplicates


We are reviewing our logic for identifying potential duplicates for births and deaths. OpenCRVS is able to flag potential duplicates on submission for the Registrar to review. They are then presented with the matched records for them to compare against; to help make an informed decision.

It would be very helpful to learn more about examples of duplicate records in your country.

To understand the problem more:

  • What are the common reasons why informants attempt to register an event more than once?
  • What would make you suspicious of a declaration?
  • What difficulties do you experience when trying to identify duplicate declarations?

To build OpenCRVS to your needs:

  • What would you like the system to automatically flag?

An example would be:
Problem: We have a problem of child marriage in our country. Parents reregister their daughter to increase her age.
Solution: Check for records with the same details but the year of birth is different +/- 3 years.

Look forward to hearing your insights!


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At the time of immediate registration upon birth in the medical facility , effort should be made to capture the mother’s Unique identifier ( for example in Uganda it’s a National ID Number ) . The child is basically linked to the mother using this number. This would help during de-duplication as an algorithm can be run to make sure that no mother’s NIN unique identifier is duplicated within a period of less than 9 months. Focus is on the mother’s unique identifier because a father can practically have multiple women giving birth at the same time . The system off online should have the ability to do the duplicate check instantly by comparing the mother’s unique identifier entry within the past 9 months. Why 9 months , it’s because the mother can give birth again within 9 months after a new birth ( I hope am correct medically on this ) .


Hello @paul.kasawuli, Thank you for the swift response. Interesting insights on how it is working with national ID comparison for Uganda using the mother’s details.I will take note of the additional recommendation of the duration period of less than 9 months. Can you also share insights on what happens for the identification of duplicates for death registrations?

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For a death to be registered, the National ID Number ( NIN) of the deceased or unique identifier must be provided by the next of kin of the deceased or the person notifying the event of death.
The justification for mandatory provision of NIN during registration is for purposes of keeping the National ID Register accurate and dynamic, Once the NIN of the deceased is availed and registration of the event is undertaken the living status of the reason is changed from “Alive” to “Deceased” Before registration, a check is undertake to ascertain to validity of the NIN and current living status of the NIN in the National Identification Register
However, currently death registration is very dismal even in the presence of law that makes it mandatory to register the event of a death. The law is available and even has penalties for non-registration but there is no enforcement of the law. Enforcement in this case would have been making it mandatory for one to present a burial permit before burial
Death Certification is at a cost and also persons only come for certification if the deceased left poperty like an estate, pension, and money in the bank. You can only access these if you as the next of the kin present a death certificate of the deceased thus for persons with no estate or property ( who are the biggest percentage) there is totally no push to voluntarily notify this death if it is a community death ( death at home ).
At least for health facilities, it is the role of the health facility to notify the registration body of this event that has occurred within their area of jurisdiction. However, majority of the death notifications from health facilities cannot be registered because the health facility personnel did not avail the NIN of the deceased. Most times the facility personnel shall inform you that the family of the deceased did not avail the National ID of the deceased when they came to pick the body of the burial. The deceased might have come to hospital without any documentation where this can be copied from. There is also not standard practice that before admission of a patient, the facility personnel must capture their National unique identifier on their admission file.
Death Certification in the country is at a cost and also persons only come for certification if the deceased left poperty like an estate, pension, and money in the bank. You can only access these if you as the next of the kin present a death certificate of the owner.

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Problem: We have a problem of change of naming because at immediate birth most of the children don’t have a name readily available due to cultural practices and thus the child’s name is listed as “ Baby of Mother’s Name” “. However once the child is given an official name upon completion of the cultural functions, parents shall go and register that birth as a fresh one without referring to the initial registration yet they would only be going to have the name updated.

Solution: When registering an immediate birth, make it mandatory to capture the unique identifier or National Identification Number (NIN) of the mother and before any registration is made, a duplicate check is made against the NIN of the mother

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@paul.kasawuli Thank you for your fantastic contribution and insights.

These are both great real world examples to help us understand the requirements for our deduplication logic.

Many thanks

There are 2 main reasons I have experienced;

  1. Inability of Issuing authority to make searches and therefore issue certified copies which leaves the applicant with no choice but process the certificate afresh, and
  2. Fraud: applicant attempting to change some details on certificate and processing afresh to incorporate those changes.
    Declarations in my country are often made only when the applicant needs a certificate for some reason. It is suspicious if the applicant cant disclose what they need the certificate for unless it is a routine declaration.
    In my country, there are very common names. The order of names, therefore, matters greatly. There is a tendency to start with the surname followed by the first name! this combination of common names and different order of names tends to complicate searches and identification of duplicates. It requires a 3rd parameter to be used in the search to narrow it down for possible duplicate e.g. a date of birth or marriage and place of birth. Furthermore, the absence of permanent places of abode/addresses/administrative units complicates the de-duplication process.
    Finally if the system can automatically flag a combination of surname and first name then enable you to correlate with date of birth/marriage and finally place of birth, that would greatly facilitate de-duplication of the registers.
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From my experience as birth and death manager and now National Mortality Lead at National Civil Registration Authority in Sierra Leone, the common reasons why informants attempt to register an event more than once include:

Attempting to fraudulently obtain financial benefits or other advantages associated with the event.

Trying to game the system by registering multiple times to increase their chances of winning a prize.

Trying to manipulate the results of the event or competition Signs that would make me suspicious of a declaration include : -

Unusually frequent and rapid registration requests.

Unusual patterns of requests from the same user.

Requests for registration from the same IP address or user ID Difficulties experienced when trying to identify duplicate declarations include:

Differentiating between legitimate and fraudulent registration attempts.

Differentiating between multiple users using the same IP address to register.

Detecting attempts to use multiple user accounts to register multiple times