navigation menu – html markup

Hi! I’m having problems with the menus html markup generated by the ‘wp_list_pages’ function.

This is the code I am using:
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With two “unnested” <li tags. This way I can manage the style of each <li tag (one for the Parent page item, and another one for the children item) by separate.

Well… I hope this makes sense and someone have an idea on how to hack it.
As far as I can see this is generated in wp-includes/nav-menu-template.php