All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
What we understood from the question is that Khul' (a wife asking for divorce in return for compensation), occurred first and then after that the husband divorced his wife twice. If it is the matter then, the divorce he intends to deliver now will be the third divorce and his wife will become forbidden for him, and he can not marry her again unless she gets married to another man who divorces her after consummating the marriage with her. This ruling is true even if the Khul' is considered as an annulment of marriage and not a divorce because the husband has already delivered two divorces after the Khul'. Therefore, if he delivers the divorce now it will be the third divorce and not the first one, as the enquiring brother mentioned.
According to the majority of Muslim scholars who are of the opinion that Khul' is an irrevocable divorce, the husband’s taking his wife back at the last time was not correct, and it is not taken into consideration since he took her back after divorcing her thrice, given that Khul’ is considered a divorce, as mentioned in Fatwa 88502.
However, our advise to the husband is to refer his case to an Islamic court to look in the matter of his Khul' and the divorces which he has delivered after Khul', because giving Khul' with the words of divorce is considered a divorce, without any disagreement among scholars, and subsequently his taking his wife back at the last time was not correct according to all jurists. For more benefit, refer to Fatwa 82541.
Allaah Knows best.