$ 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
$