Provided that all of the expenses were paid in 2017, you should enter both as the amount of the education credit you can receive is tied to the total amount of expenses paid.
You should enter them one at a time, however. Do not try to add them together. After you finish entering one Form 1098-T, the program will ask you if you have another one to enter. You will get to a screen entitled "Did you go to another school in 2016?" Enter your second one then.
[Edited 1.14.18 to add screenshot to assist with a follow up comment]
