How Zapier handles duplicate data in Zaps depends on whether the step is a trigger or an action. In trigger steps, Zapier uses a process called deduplication to ensure only new data triggers a Zap. In action steps, how your Zap handles duplicate data depends on the app used in that step.
Triggers
Polling triggers
With polling triggers, Zapier periodically asks your app for data. This is called polling for new data. Your app responds by sending Zapier its latest data, which can include both new and old data.
Zapier then uses a process called deduplication to check if any of that data is new or updated. The Zap will check if there's new data by comparing each piece of data’s unique ID to IDs the Zap has received before. If the Zap sees a new ID, the Zap runs. If not, the Zap does not run.
NoteIf you have more than one Zap using the same trigger, like two Zaps using the same form as a trigger, they will all trigger. The deduplication system only checks within the same Zap.
Some apps and triggers have a second deduplication process. The Zap uses it to trigger only for specific conditions. New data usually triggers a Zap immediately, but sometimes, this can cause the Zap to trigger before you’re ready. You can use the second deduplication process to prevent this.
ExampleFor example, Google Sheets’ New Spreadsheet Row trigger will run as soon as you enter a value in any cell in a row. You can set it up so it only triggers when a cell in the row has a value in a specific column. Then, you can fill out as many cells as you want, and the Zap will only trigger once you enter a value in the cell you designated.
Instant triggers
Instant triggers do not use deduplication because apps only send new data.
Actions
How an action step handles duplicate data depends on the app's behavior.
| Behavior | Description |
| Create duplicate data | If an app allows duplicate data, Zapier will create a duplicate record. |
| Returns an error | If an app does not allow duplicate data, Zapier will return an error message. You can view it in your Zap run details. |
| Updates existing data | If an app allows updates of existing data, Zapier will update the existing data. Some apps update by overwriting existing data, while some append to existing data. Zapier recommends you test first to see what your app does. |
| Ignores duplicate data | On rare occasions, an app may ignore a duplicate that Zapier attempts to create. The app will not create duplicate data, and you will not receive an error message. |