Here below a data table of names:

To count the number of duplicate names, enter the formula in cell B2:

=spl("=?1.conj().select(~==?2).count()",A$2:A$6,A2)

Then drag B2 down to every relevant row:

esProc Desktop and Excel Processing
9.3 Judge duplication of row-based data - by whole row
9.5 Count number of repetitions of row-based data - by key column