Legally, if he was divorced from this woman, she could still receive his benefits if he had the obligation of alimony until her remarriage, and she never remarried. She would have to produce the court order to do this and it would have been logged on this form.
If he was two-timing his legal wife with an Elizabeth Granger, the woman who could prove the earlier marriage would be the winner. The 2nd wife would be the product of an illegal marriage and not entitled to money.
BUT this assumes the government noticed any funny business and acted. I would not count on this.