Invalid names for embedded resources in .NET assembly

Trying to include in a project somes .json files as embedded resources I found that some names are not managed by .NET runtime.
It seems that names that ends with a language acroym and an extension are not compiled as embedded resources.

e.g in a project with following embedded files:

<ItemGroup>
<None Include="App.config" />
<EmbeddedResource Include="CustomizableResources.RU_.json" />
<EmbeddedResource Include="CustomizableResources.other.json" />
<EmbeddedResource Include="Anything.RU.json" />
<EmbeddedResource Include="other.RU.mp3" />
<EmbeddedResource Include="other_RU.json" />
<EmbeddedResource Include="other.RU.json" />
<EmbeddedResource Include="CustomizableResources.RU.json" />
<EmbeddedResource Include="CustomizableResources.IT.json" />
</ItemGroup>

If I recall

var assembly = typeof(Program).Assembly;
var resourNames = assembly.GetManifestResourceNames();

I get only this resources:

• TestGetManifestResourceNames.CustomizableResources.RU_.json
• TestGetManifestResourceNames.CustomizableResources.other.json
• TestGetManifestResourceNames.other_RU.json