If an advertiser sends the same conversion tracking multiple times whether by mistake or from multiple tracking sources such as a pixel, postback, or other integrations, you can use deduplication to prevent duplicates.
This is done via the External ID parameter, which ensures that only one transaction is created for each unique external ID (advertiser_custom_id).
For example, if three tracking requests arrive with the same customer ID, only a single transaction will be recorded instead of three.
You might also want to check out the Recurrence type feature, which limits how many times a commission can be applied to the same conversion even without using an external ID.
