Here below is a personnel data table:

Judge whether there are duplicate data, if so, fill in 1 in corresponding Dup field, otherwise fill in 0 (the judging basis is that the data in the Name field are the same). Enter the formula in cell E2:

=spl("=if(?1.conj().select(~==?2).count()>1,1,0)",B$2:B$7,B2)

Then drag E2 down to every relevant row:

https://c.scudata.com/article/1651916536524
https://c.scudata.com/article/1655564978878
https://c.scudata.com/article/1655595805465