use strict;
use warnings;

open my $in, '<', "Textdatei" or die $!;
my %hash;
while (my $line = <$in>) {
    chomp $line;
    my ($Vorname, $Nachname) = split/\s+/, $line;
    $hash{$Vorname} = $Nachname;
}
close $in;

open my $out, ">", "neu" or die $!;
while ( my ($Vorname, $Nachname) = each %hash) {
    print $out "$Vorname => $Nachname\n";
}
close $out;