Conditionally format first incidence of value in array (rows AND columns)

[bigmyk2k]

I can find a lot of solutions that will highlight the first incidence of a given value in each column but I am looking for a version that will only highlight one incidence in the entire array.

The current version is as follows (array is B2:FQ450)

=COUNTIF($B$2:B2,B2)=1

 

[bigmyk2k]

Anyone?