Headcanon. Nynaeve and LPD.
This has been a headcanon of mine for awhile. There is no evidence in the books or in the answers that Jordan ever gave in Q&A session.
Nynaeve is Latra Posae Decume reborn.
In the Age of Legends (Strike at Shayol Ghul) LPD opposes Lews Therin's plan to seal the Dark One. She proposes using the Choeden Kal to raise a barrier to surround Shayol Ghul from the rest of the World in the hopes that later generations might find the answer. (I'm slightly iffy on my memor of her exact plan, but it was very much something like this) Her plan is thwarted when the Access Keys are lost, but she never changes her mind that LTT's plan is too dangerous. She was probably correct. If women had joined the Strike then the counterstroke could have tainted Saidar as well as Saidin.
In the books, Nynaeve joins Rand in using the Access Keys to cleanse Saidin and then joined him in his own strike at Shayol Ghul.
Both Nynaeve and LPD were correct in their reasoning. The Pattern reusing the same soul, in such similar situations, but with different choices and different outcomes is very much in keeping with the Pattern choosing balance.
Nynaeve didn't "fix" LPD's mistake, because LPD didn't make a mistake. Nynaeve completed the task that LPD started, just in a different manner.
This doesn't really change anything in how things worked out, but I think it adds a nice symmetry. Because history doesn't actually repeat itself, but it often rhymes.