I am trying to combine two "functions" under data validation.

First <data validation <custom<settings<allow<custom

=COUNTIF($A$3:$A$77,A63)=1
This prevents the entry of duplicates in the list

Alternatively I can use <data validation<settings<allow <list
=Named_Data_Range
This allows users to pick entries from a named range on another sheet.

But does not preclude the entry of duplicates

Is there some way of combining these two "functions" providing a drop box
list and preventing duplication.

Using Excel 2002

Many Thanks
Paul