Thanks for reaching out to the Community, @Laura. I'm here to lend a hand in clarifying your duplicate concerns.
Adding transactions instead of matching causes a duplicate entry if you already have created transactions in QuickBooks Online (QBO). As per Usman, you’re not duplicating the transactions if you’re matching them with to the bank feed and attaching receipts with them. Otherwise, you’ll have duplicate entries if you’re manually adding transactions instead of matching
Let's pull up and review your expense transaction directly from your account register. This way, we can identify why they are showing as duplicates in your Profit and Loss report.
- Go to Accounting.
- Select Chart of Accounts.
- Find your bank or credit card account.
- Under ACTION, select View register.
- review and open each of your expense transactions.
Once you have reviewed them and confirmed they are all in duplicate records, you can open and delete the duplicate, one at a time.
Here's an article you can read to learn more about how you can review a transaction: Find, review, and edit transactions in account registers.
You can also find this article helpful for your future tasks: Reconcile an account in QuickBooks Online.
I'm just a comment away if you need further assistance. Have a great day!