Required Microsoft Excel freelancer for Excel sheet to ensure no numbers are repeated job

I need an excel sheet that I will use to enter codes into. The codes will be 24 character long and will contain letters and numbers.

All these codes must be unique, so I need the excel sheet to some how warn me if I enter a code that already exists on the sheet.

Here is one example of a code:
2a01:c50e:8900:6f00:dd70:d51f:6aeb:9f57

So the excel sheet must warn me if I enter this exact code (in the same order) into the sheet again. Only if the code is eneterd in exactly the same order I should get a warning.

Skills & Expertise Required

Microsoft Excel