Allow multiple firstchild items at a given level

When you have one menu that gathers items for all languages and you want to have firstchild elements at a given level, only one of them will work.

Example:

Menu Item 1 EN <firstchild>
  Submenu item 1.1 EN
Menu Item 1 DE <firstchild>
  Submenu item 1.1 DE

If you want the Menu Item 1 to "redirect" to submenu item 1.1 - then only one of the will work. The other will not get linked at all upon form submit.
Please implement some kind of identification to allow multiple firstchild items at a given level.