@$points = sort { $a->[3] <=> $b->[3] } @$points;
foreach (@$points) {
  print " $_->[3] $_->[0] $_->[1] $_->[2] \n";
}

##</code><code>##

 1338020418 33.514447422 9.142337666 16.479736  
 1338020431 33.514425964 9.142852650 16.960449  
 1338020431 33.514425964 9.142852650 16.960449  
 1338020446 33.514318676 9.143496380 16.960449  
 1338020446 33.514318676 9.143496380 16.960449  
 1338020446 33.514318676 9.143496380 16.960449  
 1338020459 33.514211388 9.144140110 16.479736  
 1338020479 33.514125557 9.145019875 14.557007  
 1338020479 33.514125557 9.145019875 14.557007  
 1338020484 33.514104099 9.145234451 14.557007  
 1338020484 33.514104099 9.145234451 14.557007  

##</code><code>##

my @unique = uniq @$points;