How to revisit and find duplicate test cases in Test case management

We have around ~14K manual Test cases(In a Excel file), we don't have enough QA team to read and make sure test case are not duplicated.

When I Googled, I didn't find any open source tool which satisfy my requirement above.

Just wanted a software suggestion or easier way to find and remove duplicated cases from Excel.

Note: Duplicated in the sense, not exact words. but, cases delivers the same meaning.