Deduplication usually works by matching user events across devices or sessions using identifiers like cookies or hashed emails, then keeping only the first or most relevant event. Attribution windows define how far back in time a click or interaction can still get credit for a conversion, like 7-day click or 1-day view windows. Together, these rules keep reporting clean and consistent, so campaigns are not overstated. Logs and event streams help reveal overlaps, while adjustments ensure fair credit distribution across channels.