Not a good solution, but .. are matching allowed?, if yes. It is not cheaper and not more effective, but is pure perl :P :

@array = qw(1 3 4 55 4 3 4 22 1 3 4 3 2 2 3 34);

$cad=join (" ",@array);
for (@array)
{
        push @uniq, $_ if ($cad !~ /((\A| )($_)( |\Z)).*$_( |\Z)/);
}
print join (",",@uniq),"\n";
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