How to remove duplicates from CIBlockElement::GetList in Bitrix?

Question

1C-Bitrix

In general, the problem occurs because of the subquery in the filter:

/*** Поиск по торговым предложениям ***/
$arFilter["ID"] = CIBlockElement::SubQuery("PROPERTY_CML2_LINK",array('IBLOCK_ID'=>8,'ACTIVE'=>'Y',$aF));

I wanted to get rid of duplicates thanks to grouping, but it does not work:

$rsElements = CIBlockElement::GetList($arSort, $arFilter, Array('ID'), $arNavParams);

First of all, the question is why the grouping does not work and produces duplicates?