It can be done but really you are both buying the property together since it is still consider 1 property that is a multifamily. This is different than buying 2 condos or townhouses where you have more flexibility with deeding and title etc...
What you are doing is just specifying how you are managing the property. Your cpa/accountant will be able to allocated the revenue and expenses accordingly once you both meet to explain your plan.
Tom Hinz www.shortsaletosell.com