This KB shares additional considerations related to NFA handling of duplicate flows / deduplicated flows
Release : 20.2 .x/21.2.x
Component : NQRPTA - REPORTERANALYZER
NetFlow v9 or v9-compatible flow:
The Harvester identifies and deduplicates multiple flows on a single router, so you can use ingress and egress on multiple interfaces.
It is most efficient to use this option for two or three interfaces.
Although option exists to enable ingress and egress across all interfaces, but this configuration may put an unnecessary burden on the Harvester.