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;