I'm a Webflow developer, not a programmatic ad guy, but I actually deal with a parallel problem: preventing duplicate content indexing and resource loading conflicts across staging/production environments and multiple CDN endpoints. When we built Hopstack's new site, we had their 5-year-old site still getting traffic while migrating thousands of CMS resources. The single setting that saved us? Disabling the Webflow staging subdomain (/webflow.io) completely before launch. This eliminated duplicate content penalties and conflicting crawl budgets--essentially the SEO equivalent of wasted impressions hitting the same user twice. For actual deduplication across multiple sources, we use canonical tags and strict DNS-level redirects so only ONE version of each page ever gets indexed or served. In your CTV case, I'd imagine you need something similar--a single source of truth at the device ID level that tells all your SSPs "this user has been served" before they waste another impression. The Hopstack project saw zero SEO ranking drops during migration specifically because we controlled which URLs were findable. That's my playbook: kill redundancy at the infrastructure level, not after the fact.
I run a painting company in Rhode Island, not a CTV ad platform, but I've dealt with the exact same coordination problem across our crew scheduling system. When we started scaling to multiple commercial jobs--restaurants, medical facilities, schools--we had painters showing up to the same property twice because our subcontractor and in-house scheduling weren't synced. The single fix that cut our wasted labor hours by roughly 30%? We implemented a shared daily dispatch board where every crew lead marks job status in real-time before starting work. No fancy software, just a centralized checklist everyone checks first thing each morning. It's the equivalent of a universal frequency cap at the device level--one source of truth that prevents duplicate coverage. For your CTV situation, I'd focus on getting all SSPs to ping a single unified ID graph before serving. We learned the hard way that coordination has to happen *before* deployment, not after cleanup. When we painted a 40-unit apartment complex last year, we avoided re-coating finished hallways by having every painter radio-confirm locations hourly--real-time deduplication saved us 15+ gallons of wasted paint. The principle is identical whether you're managing impressions or work crews: centralize your tracking at the earliest possible decision point, and make checking that tracker non-negotiable before executing.