Perhaps the following will do what you need:

use Modern::Perl;

my ( %pairsHash, $randVal );

for ( 0 .. 9 ) {

    do { $randVal = int( rand(100) ) }
      while ( ( exists $pairsHash{$randVal} and $pairsHash{$randVal} =
+= $_ )
        or $randVal == $_ );

    $pairsHash{$_} = $randVal;
}

say "($_, $pairsHash{$_})" for sort { $a <=> $b } keys %pairsHash;
[download]

Sample output for 10 pairs:

(0, 82)
(1, 50)
(2, 6)
(3, 72)
(4, 67)
(5, 71)
(6, 40)
(7, 93)
(8, 2)
(9, 22)
[download]

The script creates unique sets of two different numbers, where the second number (0 - 99) can be repeated.

Hope this helps!