Is it possible to set up a formula within Data Validation that will highlight
a duplicate entry within certain cells within a row.

E.G.

I want the user to enter data in A1,B1,C1,D1,E1 etc, but A1, C1, E1 etc are
for staff names - I do not want a name duplicated, the same name can only
appear once in a row.

Any suggestions.

Thanks

Andrew