Which is more correct: the saying of Sheikh Al-Islam that divorce occurs and counts towards the number of divorces in an invalid marriage, or the saying of Sheikh Al-Uthaymemeen that divorce does not occur in a marriage agreed upon as void?

There is no contradiction between the fatwa of Shaykh al-Islam Ibn Taymiyyah and the words of Shaykh Ibn Uthaymeen regarding the occurrence of divorce in a disputed, invalid marriage. Both agreed that divorce occurs if the husband believed in the validity of the disputed marriage. Thus, divorce occurs in a marriage agreed upon as valid, and divorce does not occur in a marriage agreed upon as invalid. As for the disputed marriage, divorce occurs if the married person believed in its validity.