The first call to registerAppForAdNetworkAttribution() generates the notification if the device has attribution data for that app, and starts a 24-hour timer. Subsequent calls to this method have no effect, and there is no need to worry about duplicates.
However, it's critical to ensure only one source is managing updateConversionValue(_:) calls. If you have more than one party making these updates, your data will quickly become messy because each party will likely define the meaning of a given conversion value differently.