Your desire to want to kill people is not normal or healthy. It is a sign that something may be wrong. It is also a sign that you should seek help immediately.
You described several symptoms that are concerning and potentially indicative of a mental illness. These symptoms include: the fact that you cannot tell if you are dreaming or not, believing that there are two demons giving you commands and your belief that you are their “agent.” Those may be signs of a break with reality.
To answer your questions directly, it is abnormal to want to kill people and to be experiencing symptoms that may be consistent with a break with reality.
Yes, you should speak to your parents about your symptoms. Request that they have you evaluated by a mental health professional. If your parents do not take your request seriously, I would recommend having them read my response to your questions. It is imperative that you seek help immediately for these issues. If you are experiencing a break with reality or are on the verge of a break with reality, there are treatments available that can prevent such an occurrence. One should always attempt to prevent a psychotic episode when possible.
I only have a very limited amount of information and thus cannot determine with any certainty whether you have a mental illness. That is why it is imperative that you receive an in-person, psychological evaluation to determine what if anything may be wrong.
I hope that you are able to receive the help that you deserve. Do not ignore your symptoms and ask for help immediately. Please take care.