Bilingual page single host problem with menu

I set up a page in our company with hugo. Since there are some employee from foreign countries some of the content must be translated to english.

There are 4 sections, each represented by a folder.
In each of these folders there is a _index.md

I used this approach: Single-Domain Bilingual Site 20180205

The config.toml goes like this:

baseurl        = "http://internal.address.tld"
languageCode   = "de-DE"
uglyURLs       = true            
relativeURLs   = true
canonifyURLs   = false    
theme          = "own-theme"

PreserveTaxonomyNames = true       

DefaultContentLanguage = "de"

[languages]
[languages.de]
languageName = "deutsch"
title = "klasdfklasf - Info-Seiten"
weight = 1

[languages.en]
languageName = "english"
title = "klsdfklsjkldf Info Site"
weight = 2

SectionPagesMenu = "main"   

and then in each _index.md I have a frontmatter like this:

+++
date               = "2017-01-01"
title              = "Aktuelle Kurznachrichten"
linktitle          = "Blog"
description        = "Das Blog enthält Beiträge zu allen Themen, die mehr oder weniger aktuellen Bezug haben. Die Beiträge sind zusätzlich auch thematisch geordnet"

[menu]
   [menu.main]
     name = "Blog"
     url = "/blog.html"
     weight = 10
+++

This works for the (default) German pages and builds a correct menu. Then I set up all the pages _index.en.md in each of the sections like this

+++
date               = "2017-01-01"
title              = "Latest news in brief"
linktitle          = "News"
description        = "The blog contains articles on all topics that are more or less up to date. The contributions are also sorted by topic"

[menu]
   [menu.main]
     name = "News"
     url = "/blog.html"
     weight = 10
+++

and I got the correct menu in the German part of the homepage, but each menu entry appeared twice in the English part of the homepage in /en, once with the english and once with the german title. Both were linked to the english content though.

I changed the frontmatter of the english files by adding an identifier:

+++
date               = "2017-01-01"
title              = "Latest news in brief"
linktitle          = "News"
description        = "The blog contains articles on all topics that are more or less up to date. The contributions are also sorted by topic"

[menu]
   [menu.main]
     name = "News"
     identifier = "blog"
     url = "/blog.html"
     weight = 10
+++

and thus was able to have the menu entries only once in the english part of the homepage also.

But: Hugo (0.36) is complaining:

hugo server -w -D -F --disableFastRender
←[?25lBuilding sites . ERROR 2018/02/15 12:48:12 Two or more menu items have the same name/identifier in Menu "main": "section1".
Rename or set an unique identifier.
ERROR 2018/02/15 12:48:12 Two or more menu items have the same name/identifier in Menu "main": "section2".
Rename or set an unique identifier.
ERROR 2018/02/15 12:48:12 Two or more menu items have the same name/identifier in Menu "main": "section3".
Rename or set an unique identifier.
ERROR 2018/02/15 12:48:12 Two or more menu items have the same name/identifier in Menu "main": "blog".
Rename or set an unique identifier.
←[K25h

According to the docs https://gohugo.io/templates/menu-templates/#site-config-menus

The identifier must match the section name.

I cannot change it’s value since english and german pages reside inside the same content subfolder = section.

After reading this https://gohugo.io/content-management/menus/#nesting I got the impression name and identifier are more or less the same so I changed the frontmatter again.
I thought I should change the name variable to the correct section name - but nothing changed:

+++
date               = "2017-01-01"
title              = "Latest news in brief"
linktitle          = "News"
description        = "The blog contains articles on all topics that are more or less up to date. The contributions are also sorted by topic"

[menu]
   [menu.main]
     name = "blog"
     url = "/blog.html"
     weight = 10
+++

Hugo is still complaining about

ERROR 2018/02/15 16:37:57 Two or more menu items have the same name/identifier in Menu “main”:

I don’t really know how to solve this.

I also find the menu entries not sorted by weight according to the frontmatter, but alphabetically.