I need a formula or a macro, that counts the total of visits of clients that
have come in more than once. All one visit clients i want them ignored.

Ex in Column A "Client Names" i have a thousand names.

John Dow
John Dow
Brian McKarther
Julian Mazilu
Chris Smith
Chris Smith

The total of repeat clients visits should be ... 4 visits.
Since "john dow" came twice and "Chris Smith" came twice also = 4 . Brian
and Julian should not be counted.
How can i get a formula to count that for me.