---
title: How to Avoid Downloading the Same Companies Twice
description: Learn how to deduplicate your company exports month over month by duplicating your company list and using it as an exclusion filter in TheirStack.
url: https://theirstack.com/en/docs/guides/how-to-avoid-downloading-same-companies-twice
---

If you run recurring [company searches](/en/docs/app/company-search) — for example, exporting companies using a specific technology every month — you'll want to make sure you're only getting **new** companies each time, not re-downloading the ones you already exported.

This guide shows you how to use [company lists](/en/docs/app/company-lists) to keep track of what you've already exported and exclude those companies from future searches.

## Step-by-step: deduplicate your monthly exports

1.  **Before your new export, duplicate your current company list**
    
    Go to [Company Lists](https://app.theirstack.com/company-list), find the list from your previous search (or the [Companies Seen](/en/docs/app/company-lists/companies-seen) list), and click the **three-dot menu** on the right. Select **Duplicate**.
    
2.  **Rename the duplicated list**
    
    The duplicated list will appear as "Your list (copy)". Rename it to something that identifies the time period — for example, "Exported April 2026" or "Companies seen until April 2026". This way, you'll have a snapshot of all the companies you had at that point in time.
    
3.  **Add the exclusion filter to your new search**
    
    Open a new [company search](https://app.theirstack.com/search/companies/new), apply your usual filters (technology, country, industry, etc.), and then click **Add Filter**. Search for "Company List" and select it.
    
    Change the operator to **is not any of** and select the list you just duplicated.
    
4.  **Run the search and export**
    
    Click **Search**. Your results will now only show companies that are **not** in your previous export list — meaning you'll only download new companies.
    
    Export the results as usual (CSV, Excel, or via [webhooks](/en/docs/webhooks)).
    

## Repeat every month

Each time you want to do a fresh export:

1.  **Duplicate** your company list (or the Companies Seen list) to create a snapshot
2.  **Rename** it with the current date
3.  **Filter** your new search to exclude that snapshot
4.  **Export** the new results

This way, you build up a history of snapshots (e.g., "Exported Jan 2026", "Exported Feb 2026") and each export only contains companies you haven't downloaded before.

## Further reading

[/docs/app/company-lists](/docs/app/company-lists)[/docs/app/company-lists/companies-seen](/docs/app/company-lists/companies-seen)[/docs/app/company-search](/docs/app/company-search)[/docs/guides/how-to-exclude-companies-from-a-search](/docs/guides/how-to-exclude-companies-from-a-search)