A procedure for deduplicating the same impression sold by multiple SSPs

A procedure for deduplicating the same impression sold by multiple SSPs

When one publisher impression is auctioned simultaneously across several SSPs, your DSP can bid against itself. Here's how to detect and stop it.

1. In your bid logs, identify candidate duplicates: requests within a tight time window (often under 200ms) carrying the same publisher domain, same user/device ID, and same slot dimensions.

2. Confirm they're the same opportunity by checking whether winning one suppresses delivery — if you win two SSPs for one slot, one is a discarded duplicate you paid to evaluate.

3. Rank the duplicate SSPs per publisher by your historical clear price and supply chain length. The shortest, cheapest path wins.

4. Suppress bids on the redundant paths for that publisher, or apply a deduplication rule if your DSP exposes one keyed on the request fingerprint.

5. Measure QPS reclaimed and any change in win rate — true dedup should hold win rate while cutting request volume.

6. Re-audit monthly; SSPs add and drop publisher integrations constantly.

Why it matters: Bidding against yourself inflates clearing prices and burns QPS on impressions you can only win once. Fingerprinting duplicates from request metadata lets you collapse redundant supply to a single clean path — the same impression, bought once, through the cheapest verified route.