(女 vs 女): Unicode points U+5973 vs U+F981
Astoundingly, while there are explanations as to why these events happen in general, there is none concerning the actual symbol under question.

U+F981 exists for the reason of Korean standard KS X 1001, the primary Korean standard. It has a peculiar feature: it has multiple actual duplicate characters. For some reason, the standard decided: if a character has N Korean readings, it will be encoded N times, in locations corresponding to all readings.

女 was encoded twice, due to the process of N-erosion in Korean: once, as Row 50 Character 19, with the other starting with [n], for the reading nyeo, another time as Row 69 Character 92, with other the other starting with [yeo], for the reading yeo. Hence, for a backwards compatibility with this standard, Unicode encoded the character once – but added another codepoint at U+F981, to guarantee that the Korean texts typed in some environment where the difference was vital (I don’t know, perhaps to make readings recoverable?), then the Row 50 character goes to the normal one, and the Row 69 one maps to the compatibility one.

There is lots of stuff in Unicode made for backwards compatibility, deal with it.