#/usr/bin/perl -w

use strict;

my @array1 = ('one','two','one','three','four','two','one');
my @array2 = ();
my $index;
my $in;

foreach $in (@array1) {
  push(@array2,$in) if (!grep $array2[$_] eq $in, 0 .. $#array2);
}

print "@array1\n";
print "@array2\n";
__DATA__
# the result :
one two one three four two one
one two three four