my %seen ;
open(DATA, "<", "names.txt") or die "cannot open names.txt" ;

while (<DATA>) {
$line = $_ ;
@array = split(/,/ , $line ) ;
$name = $array[0] ;
$amount = $array[1];

$seen{$name}++;

 if ( $seen{$name} > 1 ) { 
                                     print "$name occurs more than once" ;
                                    }