#!usr/bin/perl
use say;
use strict;
use warnings;

open(my $fh1, ">>", "output1.txt")
    or die "Can't open > output1.txt: $!";

open(my $fh2, ">>", "output2.txt")
	or die "Can't open > output2.txt: $!";

my $count = 1;
while (<>) { # Read all files that provided through ARGV
    chomp;
    if ($count == 1 or $count == 2) {
	say $fh1 $_;
    }
    elsif ($count == 3 or $count == 4) {
	say $fh2 $_;
    }
    if ($count == 4) {
	$count = 1;
    }
    else {
	$count++;
    }
} continue {
    close ARGV if eof; # reset $. each file
}

close($fh1)
    or warn "Can't close output1.txt: $!";

close($fh2)
    or warn "Can't close output2.txt: $!";

__END__

$ cat output1.txt
Sample of text line 1
Sample of text line 2
Sample of text line 5
Sample of text line 6
$ cat output2.txt
Sample of text line 3
Sample of text line 4