$ perl -le '
my @arry = qw/ a b cd gefge hhi jjkk l m nn o /;
print q{Originals: }, join q{ }, @arry;
my @n_arry = 
    grep { if ( $_ !~ m/(.).*?\g-1/ ) { $_; } } @arry;
print q{Uniques:   }, join q{ }, @n_arry;
'
Originals: a b cd gefeg hhi jjk l m nn o
Uniques:   a b cd l m o
$

##</code><code>##

$ perl -le '
my @arry = qw/ a b cd gefge hhi jjkk l m nn o /;
print q{Originals: }, join q{ }, @arry;
my @n_arry = 
    map  { $_->{ori} }
    grep { if ( $_->{ordered} !~ m/(.).*?\g-1/gx ) { $_; } }
    map  { my $str = my $o_str = $_;
           my @p = sort { $a cmp $b } split //, $o_str;
           $str = join q{ }, @p;
           { ori => $o_str, ordered => $str, };
         } @arry;
print q{Uniques:   }, join q{ }, @n_arry;
'
Originals: a b cd gefeg hhi jjk l m nn o
Uniques:   a b cd l m o
$

##</code><code>##

$ perl -le '
my $str = shift; 
print q{Original: }, $str; 
print q{Unique:   }, 
        grep { if ( $_ !~ m/(.).*?\g-1/ ) { $_; }; } ( $str, );
' foobar
Original: foobar
Unique:   
$ perl -le '
my $str = shift;
print q{Original: }, $str;
print q{Unique:   },
        grep { if ( $_ !~ m/(.).*?\g-1/ ) { $_; }; } ( $str, );
' bar
Original: bar
Unique:   bar