I also don't know what "ORL" is?
Otolaryngology?
First off, you have to know what is early match, and what is "normal" match (NRMP), which is later, in March. Neuro is an early match, so unless your first choice is an early match specialty as well, it would not be wise to use neuro as your back-up.
If you are trying to match something that is early match (ophtho, urology, etc.), then having a back-up in something that is a later match is not a bad idea. The only problem is that for very competitive specialties, even if you are a stellar applicant, you are usually advised to apply to a large and wide number of programs -- I know of people applying to urology and derm who are applying to 50-60 programs, and trying to go on 10-15 interviews. The cost and time involved in applying to a "back-up" program may be logistically too difficult to manage (ie, would you really want to cram on at least an additional 8-10 interviews in your back-up specialty, and could you do that?)
People do occasionally apply to more than one specialty at a time (I'm doing it right now), but it is not the norm, and apparently deans at some specific medical schools specifically discourage it (likely for some of the reasons listed above).
It's good to consider your career options at this stage in the game, but I would wait till the summer before your fourth year to truly start worrying about this. Things may change considerably over the next two years for you (it does happen), and your dean (most schools require that you meet in the summer prior to applying) will likely have the best advice for you, based on your career goals and performance to date. Good luck.