Usually twins will not only look the same, but also have the same interests, aspirations, and desires in life. Sometimes this is not so. Though there may be moral disparity between actual biological twins, the term is more often a misnomer. In many cases, the two look-alikes are not actually twins. In others, the so-called "evil" twin is more precisely a dual opposite to their "good" counterpart, possessing at least some commonality with the value system of the protagonist.
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