# Dedupe a Spreadsheet Before a CRM Import | Dedupely

> Find and merge duplicate rows in your CSV or Excel list before it reaches your CRM, then catch the rows that match records you already have.

- URL: https://dedupe.ly/knowledge-base/dedupe-a-list-before-you-import-it
- Section: knowledge-base
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- Any page: append `.md` to its URL for this plain-text form

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## Dedupe a List Before You Import It

By
[Gaby Salinas](https://www.linkedin.com/in/gbyslns)
Updated October 30, 2026
Keep event lists, purchased lists and exports from adding duplicates to your CRM.
The best time to dedupe a list is before you import it. In Dedupely, you upload the list as a CSV file, merge its duplicate rows, export a clean file, and import that file into your CRM. Then you run a Duplicate Search in your CRM to catch the rows that match records you already have. Spreadsheet uploads are unlimited in every Dedupely plan and the 7-day free trial, and spreadsheet records don't count toward your plan's record limit.

### Before you start

-
**Your list saved as CSV.** If it's in Excel or Google Sheets, save or download it as CSV first. See [Merge duplicates in spreadsheets](https://dedupe.ly/knowledge-base/merge-duplicates-in-spreadsheets).
- **A header row** with the column names in the first row.

### Why dedupe a list before you import it?

Your CRM's own import checks catch some duplicates, but not all of them. HubSpot, for example, matches imported contacts on exact email and companies on domain. A row without an email or domain creates a new record, and so does a row where the email is spelled differently.
Once a duplicate is in your CRM, it can pick up activities, deals and workflow enrollments, which makes it harder to merge. A duplicate row in a spreadsheet has none of that, so it's quicker and safer to merge there.
| Where you merge | What's at stake | Undo |
| --- | --- | --- |
| **In the spreadsheet** (before import) | Only rows in a file | Upload the original file again |
| **In your CRM** (after import) | Records with activities, deals, owners and workflows | Most merges, for 30 days, from Merge History |

### Which lists should you dedupe first?

- **Event and webinar lists:** the same person registers twice, or registers and checks in under different emails.
- **Purchased or enriched lists:** company names and domains are written in several ways.
- **Exports from another tool or CRM:** records that were already duplicated in the old system come with them.
- **Lists built by several people:** each person adds the same contacts, formatted differently.

### One file or several?

If your duplicates are spread across several files (for example, three event lists), upload them into **one CSV instance**. Dedupely treats them as one list, so a person in two files shows up as one match. Make sure the column headers are spelled the same in every file, or they become separate fields.
If you want to keep each list apart, upload each file as its own CSV instance.

### How to dedupe a list before importing it

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**Upload the file.** Click the **CRM** icon in the left menu, then **+ Add New CRM or CSV**, and upload your CSV under **Other Data Sources**.
-
**Mark multi-value columns.** In **Edit CSV Settings** → **Fields**, check **Multi-value**
for columns that hold several values in one cell.
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**Create a Duplicate Search** on at least three fields, like First Name, Last Name and Email. See [How to Find Duplicates](https://dedupe.ly/knowledge-base/how-to-find-duplicates).
-
**Set Merge Rules**, e.g. a Primary Record rule, and **Append** on multi-value columns so no value is lost. See [Merge Rules](https://dedupe.ly/knowledge-base/merge-rules).
- **Review and merge.** Reject matches that aren't duplicates, then bulk merge the rest.
-
**Export.** In **Edit CSV Settings** → **General**, click **Create Export**
and choose the fields to include.
- **Import the clean file into your CRM**, mapping its unique identifier (email, domain or record ID) so your CRM can match rows to existing records.

### How to catch rows that match records already in your CRM

Deduping the file removes duplicates inside the list. Some rows will still match records already in your CRM under a different email or a slightly different name. To catch them:
- After the import, open a Duplicate Search for that object in your CRM.
-
Add a filter so the search only shows matches that include a newly imported record: field *Create Date*, Applies to *one or more*, operator *is within the past (days)* with the number of days since the import, or
*comes after* with the day before the import.
- Click **Scan**, review the matches, and merge them.
Turn on [Auto Match](https://dedupe.ly/knowledge-base/auto-match)
on that search if you import lists often, so you're emailed when new matches build up.

### Example setup

An events team imports three webinar registration lists every quarter.
- **Upload** all three files into one CSV instance called "Q4 webinars".
- **Duplicate Search:** First Name: Exact · Last Name: Exact · Email: Exact, to merge people who registered twice with the same email.
-
**Second Duplicate Search:** First Name: Similar Words (Any Order) with **Match nicknames** on · Last Name: Exact · Company: Similar Words (Any Order) with Ignored terms *Inc.*, *LLC*, *Ltd.*, to catch "Bob" and "Robert" from the same company.
-
**Merge Rules:** Primary Record set to **Most Field Data**, so the row with the most information survives.
- **Export** the clean file and import it into the CRM.
-
**After the import:** add a filter on Create Date (*is within the past (days)*: 1, Applies to *one or more*) to the CRM's contacts search, scan, and merge the matches that include a new record.

### Common mistakes

- **Importing first and deduping later.** Duplicates in the CRM are harder to merge. Dedupe the file first.
- **Different headers in each file.** "E-mail" and "Email" become two fields, so the files don't match each other. Rename the headers before uploading.
-
**Forgetting multi-value columns.** Without **Multi-value** and **Append**, a merge keeps one value from that column and drops the others.
- **Importing without an identifier.** Without an email, domain or record ID mapped, your CRM can't match rows to existing records and creates new ones.
- **Stopping at the file.** The list can be free of duplicates and still match records already in your CRM. Scan after the import.

### FAQs about deduping lists before an import

-
**Can I upload an Excel file?** Save it as CSV first. Dedupely accepts CSV files, including ones exported from Excel and Google Sheets.
-
**Do spreadsheet records count toward my plan?** No. Spreadsheet uploads are unlimited and don't count toward your plan's record limit.
-
**Can I dedupe several files at once?** Yes. Upload them into one CSV instance, up to 10 files per upload.
-
**Does merging a spreadsheet change my CRM?** No. Spreadsheet merges stay in Dedupely until you export the file and import it yourself.
-
**Can I dedupe a list without connecting a CRM?** Yes. You don't need a CRM to dedupe spreadsheets.
-
**Can Dedupely compare my file with the records already in my CRM?** No. Dedupely dedupes the file on its own. Import it, then scan your CRM search to catch rows that match existing records.
-
**How big can my file be?** Up to 100 MB in total and 1,000,000 rows. See the full limits in [Merge duplicates in spreadsheets](https://dedupe.ly/knowledge-base/merge-duplicates-in-spreadsheets).

### Next up

[Merge duplicates in spreadsheets Upload your file, see the limits, and export a clean CSV.](https://dedupe.ly/knowledge-base/merge-duplicates-in-spreadsheets)

### Still stuck?

Our team helps on every plan and during the free trial, by chat, email or Zoom.
-
Need help? [Talk to support](https://dedupe.ly/contact)
-
Questions about plans? [Book a Zoom with sales](https://meetings.dedupe.ly/meetings/gaby-salinas/talk-to-sales)
-
Reading this with a model? [Read this page as Markdown](https://dedupe.ly/knowledge-base/dedupe-a-list-before-you-import-it.md)
-
Feeding it the whole site? [Read llms.txt](https://dedupe.ly/llms.txt)
Behind the article

### Gaby Salinas

Marketing Assistant at Dedupely
Gaby Salinas came to CRM data from marketing and advertising, so she looks at duplicates from two sides: the match and merge logic behind them, and what they do to the people using the CRM, like the rep who calls a customer twice, the admin who gets blamed and the cleanup nobody wants to start.
As Marketing Assistant at Dedupely, she follows how RevOps teams, end users, consultants and technical teams actually work with their data: the records they stop trusting, the workarounds they build and the moment they finally decide to clean up. What she finds shapes most of what Dedupely publishes.
[Connect with Gaby on LinkedIn](https://www.linkedin.com/in/gbyslns)

### Get started for free

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