Can a person with multiple personality disorder have one of their personality based on a real person? Can a person with multiple personality disorder have one of their personality based on a real person encountered during their lifetime? For example, in a family with multiple children, can one of the children with multiple presonality disorder have one of their personas be a "clone" of sibling? If so, how close are the two, and more interestingly, what happens when the two meet?

This question is related to this one about isolated internal representation of people, and potentially to the phenomenon of imprinting
The article you link to is fairly comprehensive, and probably already answers your questions.


Dissociative Identity Disorder is no longer referred to as multiple personality disorder.  This is a highly misunderstood disorder, and involves many possible symptoms besides the appearance of "alters".  "The diagnosis itself remains controversial among mental health professionals."
"It is now acknowledged that these dissociated states are not fully mature personalities, but rather they represent a disjointed sense of identity."  This answers your question about how close a "clone" personality would be to the real thing - ie, only in a limited sense.
Similarly, note that in most cases this disorder manifests in childhood "(usually before age 9)".  While I don't doubt that "alters" are modelled on people (fictional and real) that the patient has observed in their past, any actor will tell you that creating a "clone" personality takes a lot of work, and is likely far too much to expect of a child, let alone one suffering from the extreme level of abuse or neglect that typically initiates this disorder.
"Sometimes the alters are imaginary people; sometimes they are animals."  So while I can't say for sure if it's possible for an "alter" to be an imitation of a real person, it's certainly not common.
Moreover, it is believed that "The distinct personalities may serve diverse roles in helping the individual cope with life's dilemmas."  In other words, "alters" are formed to avoid stress, not increase it, so it wouldn't be in the patient's interest to imitate a real person.
Finally, "Environmental triggers or life events cause a sudden shift from one alter or personality to another," so this is the likely outcome should a "clone" alter meet its inspiration.