Excluding files with MsBuild ItemGroup

Question

Take, for example, the following msbuild file and directory structure:

<Project DefaultTargets="Test"
    xmlns="http://schemas.microsoft.com/developer/msbuild/2003"&gt;
   <ItemGroup>
      <FileList Include="Tests\**" Exclude="Tests\Folder2\**" />
   </ItemGroup>

   <Target Name="Test">
     <Message Text="@(FileList->'%(RecursiveDir)%(Filename)%(Extension)', '%0D%0A')" />
   </Target>
</Project>

and

Tests
-- Folder1
    -- folder1-test1.txt
    -- folder1-test2.txt
-- Folder2
   -- folder2-test1.txt
   -- folder2-test2.txt

This will produce the expected results:

Folder1\folder1-test1.txt
Folder1\folder1-test2.txt

However if I change the FileList ItemGroup to any of the following it lists all 4 files.

<FileList Include="Tests\**" Exclude="Tests/Folder2/**"/>
<FileList Include="Tests/**" Exclude="Tests\Folder2\**"/>
<FileList Include="Tests/**" Exclude="Tests/Folder2/**"/>
<FileList Include="Tests\\**" Exclude="Tests\Folder2\**"/>
<FileList Include="Tests\..\Tests\**" Exclude="Tests\Folder2\**"/>

Is this intended behavior and if so why?