is it possible prevent duplicated data for three column matches?

hello
i'm asking if there is way by code in worksheet change to prevent duplicated data in three columns are matched what I would prevent duplicated after write in column 3 for instance
I have this data as my sample
1200R20 G580 THI
if I repeat data in column a,b and when I repeat also column 3 then show me message and clear the cell until get in a new data
by the way this simple sample but my real data contain at least 1000 rows
thanks

Please try

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or use Custom data validation applies to C2:Cxx

=COUNTIFS(A:A,A2,B:B,B2,C:C,C2)=1

Try

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