for my $key ( keys %hash ) {
    delete $hash{$key}; 
    $hash{$key} = "$key_x";
}

##</code><code>##

$VAR1 = {
          '.1.3.5.7.9.1.6227.1.20.1.1.2.33.0.7.7' => 'number: 2',
          '.1.3.5.7.9.1.6227.1.20.1.4.8.88.6.3' => 'number: 2',
          '.1.3.5.7.9.1.6227.1.20.1.5.3.5.2' => 'number: 3',
          '.1.3.5.7.9.1.6227.1.20.1.6.2.88.2.3.30.4' => 'number: 3',
          '.1.3.5.7.9.1.6227.1.20.1.1.7.88.5.3' => 'number: 3',
          '.1.3.5.7.9.1.6227.1.20.1.1.6.22.2.3.30' => 'data: ',
          '.1.3.5.7.9.1.6227.1.20.1.2.9.88.2.3.30.4' => 'number: 3',
          '.1.3.5.7.9.1.6227.1.20.1.5.8.88.2.3.30.4' => '',
          '.1.3.5.7.9.1.6227.1.20.1.6.4.88.2.3.30.4' => 'number: 1',
          '.1.3.5.7.9.1.6227.1.20.1.7.3.88.2.3.30.4' => 'number: 2',
          '.1.3.5.7.9.1.6227.1.20.1.8.2.88.2.3.30.4' => 'number: 3',
          '.1.3.5.7.9.1.6227.1.20.1.9.1.88.2.3.30.4' => 'number: 4',
          '.1.3.5.7.9.1.6227.1.20.1.9.2.88.2.3.30.4' => 'number: 5',
          '.1.3.5.7.9.1.6227.1.20.1.3.3.88.2.3.30' => 'number: 6',
          '.1.3.5.7.9.1.6227.1.20.1.6.9.0' => 'number: 7',
          '.1.3.5.7.9.1.6227.1.20.1.7.1.88.2.3.30.4' => 'data: ',
          '.1.3.5.7.9.1.6227.1.20.1.8.1.88.2.3.30.4' => 'number: 8'
        };

##</code><code>##

SOME-DATA.6227.1.20.1.1.2.33.0.7.7' = 'number: 2',
SOME-DATA.6227.1.20.1.4.8.88.6.3' = 'number: 2',
SOME-DATA.6227.1.20.1.5.3.5.2' = 'number: 3',
SOME-DATA.6227.1.20.1.6.2.88.2.3.30.4' = 'number: 3',
SOME-DATA.6227.1.20.1.1.7.88.5.3' = 'number: 3',
SOME-DATA.6227.1.20.1.1.6.22.2.3.30' = 'data: ',
SOME-DATA.6227.1.20.1.2.9.88.2.3.30.4' = 'number: 3',
SOME-DATA.6227.1.20.1.5.8.88.2.3.30.4' = '',
SOME-DATA.6227.1.20.1.6.4.88.2.3.30.4' = 'number: 1',
SOME-DATA.6227.1.20.1.7.3.88.2.3.30.4' = 'number: 2',
SOME-DATA.6227.1.20.1.8.2.88.2.3.30.4' = 'number: 3',
SOME-DATA.6227.1.20.1.9.1.88.2.3.30.4' = 'number: 4',
SOME-DATA.6227.1.20.1.9.2.88.2.3.30.4' = 'number: 5',
SOME-DATA.6227.1.20.1.3.3.88.2.3.30' = 'number: 6',
SOME-DATA.6227.1.20.1.6.9.0' = 'number: 7',
SOME-DATA.6227.1.20.1.7.1.88.2.3.30.4' = 'data: ',
SOME-DATA.6227.1.20.1.8.1.88.2.3.30.4' = 'number: 8'