$beginAddrHex     = $ARGV[0];
    $endAddrHex       = $ARGV[1];
    $numberOfSims     = $ARGV[2];

##</code><code>##

GetOptions( \%options, qw[ help+ delete+ err_dup=s{3} ] );

##</code><code>##

my %options = (
    'help'     => 0,
    'delete'   => 0,
    'err_dups' => [],
);

##</code><code>##

    if ( $options{ 'err_dup' } ){
        print "err_dup is called\n";
        my ( $beginAddrHex, $endAddrHex, $numberOfSims ) = @{ $options{ 'err_dup' } }; # or just pass the option straight to the sub you're about to call
    } else {
        print "err_dup NOT called\n";
    }

##</code><code>##

GetOptions( \%options, qw[ help+ delete+ err_dup=o{3} ] );