use strict;
use warnings;

open(FILE,"<messages.txt") or die "Unable to open file 'messages.txt':  $!\n";
open(my $daniel,">Daniel.txt") or die "Unable to open file 'Daniel.txt':  $!\n";
open(my $steffi,">Steffi.txt") or die "Unable to open file 'Steffi.txt':  $!\n";

my $fh = "none";
while (<FILE>) {
    chomp;
    if (/^\s*Daniel\s+Lastname\s*$/s) {$fh = $daniel;}
    if (/^\s*Steffi\s+Lastname\s*$/s) {$fh = $steffi;}
    if ($fh ne "none") {print $fh $_;}
}

close($steffi);
close($daniel);
close(FILE);