You could have both iterations go over the hash in an ordered manner, and then quit the inner loop after processing the key against itself. This is not tested: 

use strict;
use warnings;

#print Dumper \%hash2;
my %spair = ();
my $prod;
foreach my $si (sort { $a <=> $b } keys %hash2)
  {
    INNER: foreach my $sn (sort { $a <=> $b } keys %hash2)
      {    
         if ($si == $sn)
         {
               $prod = $hash2{$si};
               $spair{$si."-".$sn} = $prod;  #: $hash2{$si}\n";
         }
           else
         {
               $prod = $hash2{$si}*$hash2{$sn};
               $spair{$si."-".$sn} = $prod;  #: $hash2{$si}\n";
               last INNER;
         }

      }
  }
print Dumper \%spair;

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In reply to Re: Self-Looping over hash - how to remove duplicate by gaal
in thread Self-Looping over hash - how to remove duplicate by monkfan

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