You want the same variable to hold two different values in the same scope. That won't work.

Unless you do something weird like use dualvar and evaluate in number or string context to force one or another value to be used.

use strict;
use warnings;
no warnings 'uninitialized';

## not recommended
use Scalar::Util 'dualvar';

my ($test, $test2);

print sprintf('1: %s', $test), "\n";

if (not defined $test) {
    $test = dualvar(0, 'OK');
    print sprintf('2: %s', $test), "\n";
}

print sprintf('3: %s', $test > 1 ? $test : undef), "\n";

if (not defined $test2) {
    print sprintf('4: %s', $test), "\n";
}

__END__
[download]

... but really it seems like you need to rethink your program design. Can you share the big picture of what you are trying to do?

Hope this helps!