A quick trick for hiding duplicate Excel values(2 posts)
We had a similar question a couple of weeks ago.
But, in my opinion, the best solution for this type of data presentation is pivot tables that will do exactly the same thing with more functionality e.g. totals and subtotals and with about the same effort as setting up a conditional format. Also, with the pivot table your original data is preserved as is so you always can refer back to it.