To me, a unique talk is a talk that the combination of "speaker" and "title" columns are different. So with this assumption in mind you can search the database for a "speaker" & "title" and see if it still exists.

Checking talks.next() does not confirm that you removed a talk. All you are doing here is confirming that the next talk does not have the title "test title1". So what if the next().next() talk contains it?