my %seen =() ;
@unique_array = grep { ! $seen{$_}++ } @non_unique_array ;

##</code><code>##

sub dedup {
  my %seen;
  grep { ! $seen{$_}++ } @_;
}

##</code><code>##

@tapes = qw(tape1 tape2 tape1 tape3 tape2 tape1);
print join(' ',dedup(@tapes)),"\n";