Hello i am working with analytic accounts and when duplicate an record this duplicate all childs, i consider a great feature but i check the code en lines are cleaned just for record duplicated not for all childs.
You can check the copy method http://bazaar.launchpad.net/~openerp/openobject-addons/6.1/view/head:/analytic/analytic.py#L215 (here)
I want to read comments and will report as bug to read R&D team opinion.
Regards,