Distinct in Laravel 5 not working properly

I want the distinct names from my database table.The table contains column id and name.

I have tried

$diff=Crud::distinct('name')->get();
$diff=Crud::distinct()->get();

Both of them not worked.They are returning the result with duplicates.Here Crud is my eloquent model.

But when i use

$cnt=crud::distinct()->count('name'); //returns the correct count

and

$u=crud::all();
$diff=$u->unique('name'); //returns the distinct names

Why duplicate values are returned while i'm using the distinct? I want distinct names by using distinct.

Thanks.

via Chebli Mohamed