Why doesn't QBO warn me when I enter a Vendor Expense (paid w/ CC) and a Vendor Bill, with same Bill No? We are entering the same entry on accident.

Hello there, tina-segal-dss-s.

We have a preference where you can turn on the option to receive a prompt when a duplicate check or bill number is used. You can turn that on so it'll prompt moving forward. 

Let me show you how:

Go to the Gear icon and click Account and settings.

From the Advanced menu, scroll down to the Other preferences section.

Turn on the Warn if duplicate check number is used and Warn if duplicate bill number is used options.

Click Save and then Done. 

You can unlink the vendor's bill by opening the Expense and select the correct one. Read the prompt and confirm the changes. 

Here are a few articles that will help you in handling vendor reports and transactions:

• Enter and pay bills
• Common custom reports in QuickBooks Online 

Let me know if you have other questions. Take care!