Conditional format would work fine:
With cell A1:
Formula is,
=COUNTIF(A:A,A1)1
Note that if you put this formula in the column next to your data, you could
copy it down and then AutoFilter based on TRUE and whatever value is in
column A to find all the duplicates.
--
Best Regards,

Luke M
"Jeremy" wrote in message
...
Is there a way I can write a script or conditional format to identify
duplicate data. The data can be marked by highlight if need be.

Ex
Since A1 and A3 are both the same numbers both locations become
highlighted.
I have a large range of data to perform this in. The numbers being
identified are lager than 2 digits.
A
1 12
2 13
3 12


Thank you