If (and ONLY IF) you elect in the rental section to have the program do the splits for you, then you only enter it one time in the rental section of the program. You enter the 1098 *EXACTLY* as printed. The program will do the splits *for* *you* then.
Once you are long done with the rental property *AND* you are completely done with everything under the "Personal income" tab, you'll be under the Deductions and Credits tab. The first thing you deal with under Deductions and Credits is the "Your Home" section. Read the small print on each and every screen as you work through the "Your Home" section. The small print will inform you that it already has X amount of mortgage interest (as well as property taxes) allocated. That allocation will be from the total amounts you entered in the rental section. So in this case you will not, under any circumstances and with no exceptions, enter that 1098 information a second time.
