From what I understand, there are certain deeds that can make a person forbidden to enter hellfire. Likewise, there are certain deeds that also make a person forbidden to enter paradise. What would happen to a person who is forbidden from both as a result of their deeds. For example, a person who breaks ties with family members but prays all 5 prayers on time.
First of all, there is nothing without Jannat (haven) or Jahannam (hell). You can refer this to the binary digits 1 or 0. If such position happens that one has got the same points resulting tie. I think he or she must be gone to the haven depending on the consideration of Allah (SWT). Because, Allah (SWT) is so kind full. Insha Allah, he will go to the haven according to the mercy of Allah (SWT). But, the example you have given at the end of your asking, it is very tricky. I sorry, I am incapable to explain such incidence.