You don't directly depreciate over 17.93 years.
You continue to depreciate the 'carryover Basis'. So you would enter a placed in service date of 2014-ish (the placed in service date of the relinquished property). So indirectly, it will continue to depreciate the remaining Basis over another 17.93 years.
Unless the replacement properties each had the same value, you don't divide the Basis by exactly two. You divide the Basis based on the proportion of the Fair Market Value of each one. For example, if one property cost $400,000 and the other property cost $600,000, then you would allocate 40% of the Basis to one property and 60% of the Basis to the other property.
