Hi @Michele DuBose ,
The code in that article only works for single text type columns. You can noticle that columns(Title,Name,Email) used in the aritcle are all text type. While you are using Darte cloumn and Person column. These type columns will not work with the code.
So, you have to change your columns to text type to use the code. Otherwise, you have to use the OOTB that permit only one column at a time to be unique.
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