Can I safely remove these lines from zen_classic template.php?

I've got a subtheme based on zen_classic... but I want to customize the registration form. Per the D6 theming guide, that involves implementing function zen_classic_theme() in template.php, as well as adding some preprocess work and then creating a special template file.

But when I attempted that, I discovered that zen_classic already has zen_classic_theme stuff going on at line 83.
Well, I commented that out and everything seems to be fine, but since I have no idea what that code was doing, I'm uneasy.
Here are the lines in question...

<?php
function zen_classic_theme(&$existing, $type, $theme, $path) {
return zen_theme($existing, $type, $theme, $path);
}
?>

So, am I OK without them? What are they doing?