Custom validation with formula
=COUNTIF($A$1:$A$10,A1)+COUNTIF($A$15:$A$20,A1)<2

Jerry

andrewm wrote:

Hi - I have a roster in which in a range a1:a10, a15:a20 I will be
putting names in.
eg. andrew, charles, abdul, tony. Andrew or Charles, and abdul or
tony can only occur once. how can I do a data validation on this.

ie. andrew or charles can occur only once, abdul or tony can occur
only once in the ranges

A1:A10, A15:A20

thanks

andrewm