I have several categories, and would like to determine if they are unique or not.

Under the Unique column I have my expected value. The Tried colum has the "tried" formula inside.
I tried:
=IFERROR(VLOOKUP(B2;B2:B6;0;TRUE);"NOT UNIQUE")
However, this gives me NOT UNIQUE in every row.
Any recommendations what I am doing wrong?
I appreciate your reply!