Deduplication is the process Zaps use to ensure your Zap only triggers for new information, avoiding duplicates. Duplicate information is managed differently in Zap triggers and actions.
For polling triggers, Zapier stores an identifier for each item seen so that the Zap never triggers for that item again. Deduplication only happens with polling triggers. Instant triggers don't need deduplication as the app only sends new items to the Zap.
If you have two Zaps using the same trigger (for example, two Zaps using the same form as a trigger) both Zaps will be triggered by new items. The deduplication system only checks within the same Zap.
Some apps and triggers have a special post-deduplication process that prevents the Zap triggering before the item is completed. A new item usually triggers a Zap as soon as Zapier first encounters it. However, in some cases, this causes trouble as Zapier could trigger for the item before it's finished.
You might still be typing into your new Evernote note when it triggers your Zap. The post-deduplication process will wait to trigger a Zap until the item has stopped changing across one polling interval.
For actions, deduplication depends on how the connected app acts when your Zap tries to create data that already exists in that app:
- Duplication: some apps allow for duplicate records. In those cases, the Zap will create duplicates.
- Errors: if the app does not allow duplicates, the Zap will return an error message, which can be viewed in Zap History.
- Updates: some Zaps allow the Zap to update records with new information. It's important to note that updating can often mean replacing existing information. Check if there is information in the action app that you might potentially lose.
- Stop/Ignore: on rare occasions, the Zap will attempt to add a duplicate, but the action app will recognize the duplicate and take no action, without returning an error message or alerting you.