Both language menus show up
I suppose you added the french menu item before you added additional languages to your Drupal. Then it is very likely that it was saved using LANGUAGE_NEUTRAL as language and therefore will appear within all languages.

To fix this, go to the menu's item list on admin/structure and manually edit the menu item. You should find a drop down for the language within the edit form. Make sure to choose the appropriate language here and save the item.