Why would Jesus obey the request of two demons anyway? They ask to be sent into the swine and he grants them that request. Why not just destroy them or send them into a rock or something?
For those who actually believe in exorcism, knowing the demons name is a prerequisite to commanding them to leave the person. It's interesting that the account in Mark and Luke we learn of a man with a demon. The demon says "Legion, for we are many". It's only in Matthew do we read that there's actually two possessed men. And Matthew doesnt mention Legion.