After you enter the first, you will be on the Mortgage deduction summary page.  In the bottom left of the page their is a box that says "Add a lender".  Click on that box and enter your second Form 1098.  If you have already entered your first Form 1098 and need to get back to the Mortgage deduction summary page, then while logged in and working in your return:

• Click on Search
• Type Form 1098 in the search window
• Click on "Jump to Form 1098"
• That should take you to the Mortgage deduction summary page