preregister var once

[Seba123]

Hi, I have a problem

My code in showthread_postbit_create is similar to this

if($post['postcount'] == 1)
{
vB_Template::preRegister('postbit_legacy', array('myvar' => 'HELLOWORDL!'));
}

and all looks ok, but this code displays in all posts. To solve this problem, I must use code like this

if($post['postcount'] == 1)
{
vB_Template::preRegister('postbit_legacy', array('myvar' => 'HELLOWORLD!'));
}
else {
vB_Template::preRegister('postbit_legacy', array('myvar' => ''));
}

Is any other way to correctly do this?