How to display a warning of a possible duplicate entry?

Hi, Creator is looking very good as possible solution for us.

I know how to prevent dups, but would like to ask about a different scenario, please.

We are using a form to enter requests from individuals. We will only allow one request per individual, but there will be times when two different people might share the same last name. Is there a way to display a notification of a possible duplicate entry? That would allow the data entry person to check for previous requests. If none are found, we would want them to be able to proceed.

TYIA,

Mike