Do you have AEP Assurance installed in your apps for testing? Have you checked all the data that is being sent to Adobe, and also what the post-processing is doing?
There are so many potentials here, that without seeing it, it will be really hard to diagnose... the first step is to really test your implementation and try to identify where it might be happening... whether it be multiple calls (with the same data), the data being sent to Adobe being doubled, or maybe something happening during the mapping...
Figuring that out is the first step to understand and fixing the issue.