Steps to reproduce:
1. Download and open attached project "Folder Bug.zip"
2. Notice in project browser that is folder called "Plugins" which has two more folder in it "Framework" and "My.1Framework"
Both of them has identical "System.Data.Dll" file in them and everything works as expected
3. Rename "My.1Framework" to "My.Framework"

Actual result: Notice that DLL file inside is no longer recognized
Expected result: DLL is recognized regardless of the folders name

Tested and reproduced on:
Windows 10
Unity 5.1.4f1, 5.2.4p1, 5.3.3p3, 5.4.0b10