Illuminate\Database\Eloquent\Collection duplicates() doesn't work like Illuminate\Support\Collection #61595

Laravel Version

13.x

PHP Version

8.3

Database Driver & Version

MariaDb

Description

The documentation states that Illuminate\Database\Eloquent\Collection extends all the methods of Illuminate\Support\Collection,
but attempting to use ->duplicates('some_attribute') throws an unexpected exception.

I only realized this when checking the sources; should it be documented that it can't be used, or is it a bug?

Steps To Reproduce

/*
MyModel{
  id, some_attribute
}
*/
$myList = MyModel::get();
$dup1 = collect($myList)->duplicates('some_attribute'); // this works,  base collection was used
$dup2 = $myList->duplicates('some_attribute'); // unexpected exception on `$a->is($b)`