VAST-2.0-duplicate-impression
VAST-2.0-duplicate-impression
Duplicate <Impression> URL within the same <Ad>
WarningConsistencyIAB VAST 2.0 §2.3.1VAST 2.0 and later (all versions)
Short answer
Two or more <Impression> elements inside the same <Ad> carry identical URLs. The player will fire both, resulting in double-counted impressions and billing discrepancies.
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 2.0 and later (all versions).
How to fix
Remove the duplicate <Impression> URL, or change one to a different endpoint if both are intentional (e.g. two separate measurement partners).
Check your VAST tag for
VAST-2.0-duplicate-impression and other issues instantly.Open the VAST tag validator →Other Consistency rules
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