Understanding NetFlow Duplication: Why It Happens, and How to Deduplicate
Datadog, Friday, September 11th, 2026
A technical explanation of why NetFlow records duplicate across devices and how to deduplicate them correctly.
This post explains the underlying causes of NetFlow duplication, where the same traffic flow is reported by multiple devices along a path, inflating volume metrics and distorting analysis.
It covers why the duplication happens as a consequence of where exporters sit in the topology, how to prevent it through export configuration, and how deduplication works when prevention is not practical.
For network teams whose flow-based capacity planning has produced numbers that do not match reality, this is a likely explanation and a practical guide to correcting it.