A Woman Remarried Without Divorcing Her First Husband.
There’s no mention of cheating, insincerity, or irresponsibility in the question.
In my opinion either the first nikah was not valid because all the requirements were not fulfilled, or the second nikah is not valid because the divorce from the first nikah didn’t take place. Of course this kind of issues require much deeper understanding of the problem. My suggestion to you is that the woman should seek council from a qualified scholar. Should you choose to do so, please send me a PM and I can try to arrange that for that.