Yield Group vs header bidding double-counts demand

Yield Group vs header bidding double-counts demand
Confirmed: running an SSP through both a GAM Yield Group (Open Bidding) and your client-side header wrapper means the same SSP bids twice into one auction — and depending on priority, the lower bid can win the line item slot, capping your real ceiling.
— List every SSP active in both your wrapper and Open Bidding
— Pick one path per SSP or accept self-competition
Impact: dual-pathing one SSP suppresses its own best bid. Confidence: confirmed.