Hello. I do think this is happening since the implementation of
http://issues.ez.no/IssueView.php?Id=19477&activeItem=1

That added a foreach loop in design/admin2/templates/detail.tpl

{foreach $node.object.allowed_assign_section_list as $section}
...
{/foreach}

That $section is the one that throws the warning after

Warning: eZTemplate:def @ design/admin2/templates/children_detailed.tpl:1[0]	Jul 11 2012 23:15:26
Variable 'section' is already defined.

I don't know better solution than use another name for the var in the loop... do you see this ok?

Cheers

Steps to reproduce

Upgrade the code to the last rev in master branch, enter your admin site. warning should appear there.