Conditional Formatting/Duplicates

Hello all,
My background is many years of Access VBA. From time to time, I'm called upon to work in Excel. I am not that familiar with the library.

I'd like to know if it is possible to do the following:

Examine Column 1 and, for each like value, examine Columns 2 and 3 for duplicate values. Highlight or conditionally format the duplicates in Columns 2 and 3 (again, for each like value in Column 1).

Being that I've coded Access applications for quite some time, I am sure it can be done...I just don't yet know exactly how. I've searched the archive for and found some examples which deal with duplicate data, but have found none yet which quite fit my scenario.

Could someone help me out, please?

I will continue searching the many threads matching my keywords in the meantime.

Many thanks.

Oh, sorry to impose even more...I've found sample code which enforces rules and conditionally formats cells when new data is added. It works fine and I understand it. I'm hoping the kind soul who might help me with the above can explain how I might do both things on the code page.

I assume the Worksheet_Change Event would contain the "enforcement" code.