Duplicate transactions on import: how to avoid them

Asgeir Albretsen

Published 15 August 2025

When you start importing transactions from your bank into a budget app, it looks straightforward. Upload a file, and transactions appear. But there's one thing that quickly ruins the whole picture: duplicates.

Duplicate transactions make your budgets look faster than they are. Expenses are counted twice. Categories become meaningless. And even if you delete one of them afterwards, you can never be completely sure which number was right.

The good news is that duplicates are completely avoidable if you have a routine.

How duplicates happen

Most duplicates don't occur because the system makes a mistake. They happen because you import overlapping periods, or forget that you've already imported a period.

Common causes:

You import the same file twice by accident
You import the same date range from the bank twice on the same day or different days
Your bank sends you the same transaction twice (rare, but it happens)
You export from the bank with different date filters and end up with overlapping data

All of these scenarios are preventable.

Checklist before you import

Do this before you upload a file:

What is the date on the file you're about to upload? Write it down first. The bank usually shows the export date, or it's in the filename.
When did you last import? Check your transaction list. What's the date of the last transaction you already have? Make sure the new import starts after this date, not before.
Check the filename. If your bank names files with dates (for example, "transactions-1-august-to-31-august.csv"), verify that you have the correct period before importing.
Don't upload the same file twice. If you've already imported a file, don't do it again. Even if you delete the transactions later, manual errors can happen.
Import only new transactions. Each import should ideally contain only data you don't already have. Don't import "the whole year" every week just to be safe.

What if you already have duplicates?

If you discover that you've imported the same transactions multiple times:

Most budget apps let you delete transactions easily. Go through the list, identify the duplicates (same amount, same date, same recipient) and delete one of them.
Don't be afraid to adjust. If you delete a transaction that was correct, you can always import the file again and pick just that transaction.
Use your history as a guide. Note which date you last imported, and import only from the day after next time.

Best practice: one import per week

To make this easy, establish a fixed routine:

Import every week on the same day and time. For example, Monday morning or Friday afternoon.
Always export the last 7-10 days from your bank. It creates a small overlap, but you can easily identify and delete duplicates if they occur.
Check the transactions the same day. If something looks odd, it's fresh in your mind what you did.

When you import often and in small portions, it becomes impossible to forget what you've already imported. One week's worth of transactions is manageable. A whole year is not.

In Luma specifically

Luma is designed to handle import without stress. When you upload a CSV file, the system can often detect whether a transaction already exists based on date, amount, and description. But like all systems, it's not 100 percent certain.

To be sure: wait five minutes after each import and skim through the new transactions. If something looks duplicated, the easiest thing is to delete and import again.

Summary

Duplicate transactions don't need to happen. With a simple checklist before each import, and by sticking to one fixed import day per week, you keep your numbers clean and reliable.

Your financial picture is only as good as the numbers behind it. Protect them.

How duplicates happen

Most duplicates don't occur because the system makes a mistake. They happen because you import overlapping periods, or forget that you've already imported a period.

Common causes:

You import the same file twice by accident

You import the same date range from the bank twice on the same day or different days

Your bank sends you the same transaction twice (rare, but it happens)

You export from the bank with different date filters and end up with overlapping data

All of these scenarios are preventable.

Checklist before you import

Do this before you upload a file:

What is the date on the file you're about to upload? Write it down first. The bank usually shows the export date, or it's in the filename.

When did you last import? Check your transaction list. What's the date of the last transaction you already have? Make sure the new import starts after this date, not before.

Check the filename. If your bank names files with dates (for example, "transactions-1-august-to-31-august.csv"), verify that you have the correct period before importing.

Don't upload the same file twice. If you've already imported a file, don't do it again. Even if you delete the transactions later, manual errors can happen.

Import only new transactions. Each import should ideally contain only data you don't already have. Don't import "the whole year" every week just to be safe.

What if you already have duplicates?

If you discover that you've imported the same transactions multiple times:

Most budget apps let you delete transactions easily. Go through the list, identify the duplicates (same amount, same date, same recipient) and delete one of them.

Don't be afraid to adjust. If you delete a transaction that was correct, you can always import the file again and pick just that transaction.

Use your history as a guide. Note which date you last imported, and import only from the day after next time.

Best practice: one import per week

To make this easy, establish a fixed routine:

Import every week on the same day and time. For example, Monday morning or Friday afternoon.

Always export the last 7-10 days from your bank. It creates a small overlap, but you can easily identify and delete duplicates if they occur.

Check the transactions the same day. If something looks odd, it's fresh in your mind what you did.

When you import often and in small portions, it becomes impossible to forget what you've already imported. One week's worth of transactions is manageable. A whole year is not.

In Luma specifically

To be sure: wait five minutes after each import and skim through the new transactions. If something looks duplicated, the easiest thing is to delete and import again.