Hi Karin,

You've thrown me a bit of a curve ball there because you're using a Mac version of Excel. I've never used a Mac, so I'll show you how I would do it in Excel 2010 and hope that the same applies for your version.

You want to allow duplicate values but have a way to highlight them. I think a good solution here would be to use conditional formatting.

Select the column and then go to conditional formatting > highlight cell rules > duplicate values > choose the colouring you want and click OK. [See attached screenshot]. At that point any duplicate values should be highlighted.



If the "duplicate value" rule is not available in Excel 2008 then you can use this conditional formatting formula instead.
Where $A:$A is the entire column (change to $C:$C or whatever you need) and $A1 is the first cell in that column (change to $C1 or whatever you need).

Attached Images

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