i have a table like this
ID nachname vorname 1 john doe 2 john doe 3 jim doe 4 Michael Knight
The following query will give the list of duplicates :
SELECT n1.* FROM table n1 inner join table n2 on n2.vorname=n1.vorname and n2.nachname=n1.nachname where n1.id <> n2.id
BTW The data you posted seems to be wrong "Doe" and "Knight" are a lastname, not a firstname :p.