Steps to reproduce:
1. Download two files attached (16.fbx and 28.fbx)
2. Import them both to Unity by drag and dropping to project field

Actual result: In the Unity preview for these files, both of them have 16 vertices
Expected result: One has 16, the other one has 28 vertices. This can be seen correctly if the models are imported to Blender (Alternatively, this can be seen with text editor on line 218, which has all the vertices coordinates for the models. Different counts of points).

See attached screenshot from blender and text editor

Tested and reproduced on:
Windows 10
Unity 5.3.5p7, 5.4.0b24, 5.5.0a2