You have to Check your Council's Local Environmental Plan to see that after development whether you can sell one property individually and keep the one or sell them together. What I am trying to say is, Council may block you from selling one of them due to Titles, so ensure all Titles of each property is completed, with completion of the building being finalised.
I know someone that wants to live in one Town house but has to see both Town houses and moved out because of the Local Environmental Plan!