Contradiction with 1 Samuel 14:50
Michal is listed as the daughter of Saul, not Maachah.
1 Samuel 14:50: And the name of Saul's wife [was] Ahinoam, the daughter of Ahimaaz: and the name of the captain of his host [was] Abner, the son of Ner, Saul's uncle. [Abner: Heb. Abiner]
Contradiction with 2 Samuel 14:27
It states that Maacah bore Absalom’s children, but not referencing the same lineage.
2 Samuel 14:27: And unto Absalom there were born three sons, and one daughter, whose name [was] Tamar: she was a woman of a fair countenance.