You could use Conditional Formatting to color both cells when a duplicate is
entered.

Select A1:A50 and FormatCellsCFFormula is:

=COUNTIF($A$1:$A$50,A1)1

Format to a nice bright red.

To have a warning "pop up" would require VBA code or Data Validation which you
have used already.

If you did use DV you would change the formula to =COUNTIF($A$1:$A$50,A1)=1


Gord Dibben MS Excel MVP


On Sun, 11 Feb 2007 15:41:00 -0800, ElFrodo
wrote:

Hello good people!

Anyone who can help me with following problem:

I need warning to pop up when the user of a sheet is trying to put/write the
same letter, number or word in two different cells in a column.

I must mention that the cells in use are already validated, using a list
validation.

Anyone? :)

Best regards
ELFrodo