A really minor thing, but with 2.92 I’m seeing two __doc__ entries reported on a bpy_prop_collection:
>>> dir(bpy.data.objects)
['__bool__', '__contains__', '__delattr__', '__delitem__', '__doc__', '__doc__', '__getattribute__', '__getitem__', '__iter__', '__len__', '__module__', '__setattr__', '__setitem__', '__slots__', 'bl_rna', 'find', 'foreach_get', 'foreach_set', 'get', 'items', 'keys', 'new', 'remove', 'rna_type', 'tag', 'values']
Checking older versions it seems this has been the case since at least 2.79.