No you don't need it. And it's not even necessarily desirable. Socionics is right about the chemistry though.

Von Franz writes:

In marriage, as Jung points out, one tends to marry the opposite type (= dual / semi dual, my comment). And then again he is, or so he thinks for the moment, freed from the disagreeable task of confronting his inferior function. That is one of the greatest blessings and sources of happiness in the early stages of marriage; suddenly the whole weight of the inferior function is gone, one lives in a blessed oneness with the other, and every problem is solved. But if one of the partners dies, or the need comes up in one of them to develop the inferior function instead of just leaving those section of life to the other, the trouble starts.

Lectures on Jung's typology (von Franz, Hillman)

As we can see von Franz states the obvious fact that duality can be comfortable, but that things are more complicated than that.