would patients suffering frontal lobe disinhibition portray different personalities?

First of all, there would probably be a massive personality shift from before the injury. Now if you are talking after the injury if the person would be able to experience different moods like joy, happiness, anger, and sadness, I think it would depend on exactly where the injury was. I recall reading that frontal lobe injuries tend to create a "flat" demeanor. My readings didn't specify whethere there was a range of emotion, of if the emotional response was somewhat muted. I remember reading that there is a great lack of fellow feeling, and that the people are very selfish, and lack fellow feeling. One medical documentary was about a husband that had suffered brain damage to the frontal lobe. It made him incapable of loving anyone, and he was incredibly hostile. He would be extremely cruel in his comments about his wife, didn't show any emotion if that bothered her or not. It was almost like he was reading from a script when he would say horrible things to his wife. That is the amount of emotion/emotional connection he felt. He didn't seem to care about anything or anyone. It was unsettling to see.

If you are questioning whether an injury such as that would cause a shift to multiple personalities, I wouldn't think so.

Frontal Lobe Disinhibition

It's too late to think right now. But for the most part people are as similar as they are unique.