How do I fix duplicate purchase events in my Facebook Ads Manager?

Duplicate Facebook purchase events occur when both your browser-side Meta Pixel and server-side Conversions API (CAPI) report the exact same checkout transaction without matching unique event ID parameters for automatic de-duplication.

“This tends to crop up when your browser pixel and your server-side CAPI both report the same sale without a matching event ID to tell Facebook they’re duplicates. I’ll get the IDs aligned within 24 hours for $99.”
— Jeff Bollettino, Managing Director, Ignite Conversions