VAST-4.1-verification-duplicate-vendor
VAST-4.1-verification-duplicate-vendor
<AdVerifications> contains duplicate vendor identifiers
WarningConsistencyIAB VAST 4.1 §2.3VAST 4.1, 4.2, and 4.3
Short answer
Two or more <Verification> entries under <AdVerifications> share the same vendor value. Duplicate vendors cause the OM SDK to run redundant or conflicting verification sessions; each vendor should appear once.
Why this matters in production
This rule is a strong risk signal. Tags with this issue often still parse, but they become brittle across SDKs, SSAI resolvers, and CTV environments. Consistency rules catch documents that technically contain the right pieces but combine them in ways that produce conflicting signals for downstream systems. Affected scope: VAST 4.1, 4.2, and 4.3.
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