Valid question, and yes, technically you can. BUT, the real question is, is it smart?
Most schools that offer deferments will make you sign a contract saying that you will not apply anywhere else during your year of deferment, with varying consequences if you do. Ultimately, it's not worth the risk of losing out on an acceptance and possibly being blackballed by the rest of the DO schools, who will most certainly be told that you have been accepted before (either by you on the application where it asks if you have applied or been accepted, or by the DO school that granted your deferment) Now, if you plan on applying MD and are sure that you can get in, it may be a different story since the application isn't shared with DO schools and most DO schools don't interact with MD schools (except Texas)
Bottom line, I would strongly advise against doing it. If you think you would rather apply next year with an updated app (say you're in the middle of finishing a graduate degree, or some pre-reqs, or retaking the MCAT, etc.) then just don't apply this year. I'd rather sacrifice a year and improve my app in order to have a better chance at getting into my preferred school than get in one year earlier and spend 4 years somewhere I don't want to be.