<<<"I would much prefer this ridiculous waste of all our time ends here. It
gets
none of us anywhere.">>>
I accept that statement!
Getting back to the nuts and bolts of your question, what happened when you
tried (assume you *did* try) the array formula I posted in the misc. group?
=IF(MAX(COUNTIF(B20:R20,B20:R20))>1,"Duplication","OK")
--
Array formulas must be entered with CSE, <Ctrl> <Shift > <Enter>, instead of
the regular <Enter>, which will *automatically* enclose the formula in curly
brackets, which *cannot* be done manually.
You *must also* use CSE when revising the formula.
Do a test on a new, blank sheet, where you enter various team names, and
you'll see that any duplicates will make the formula return notification
dupes.
You also have an option using "Data Validation" of *preventing* duplicates
from being entered in the first place.
You have an additional option of *flagging* duplicates ... say, turning the
cell red if any dupes are present.
You have a lot of ways to go.
Waiting on you for additional input.