Yes, tutors can teach back to back sessions but it is important to pay special attention to time keeping.
If a back-to-back booking was made by the same student, there is no need to quit one session and connect to the next one. However, two feedback forms will need to be submitted in order to generate payment for both sessions.
If all the slots are booked by different students, it is strongly recommended that tutors schedule breaks (remove slots) in order not to allow too many sessions in a row and always ensure highest quality tutoring.
For more information see this post.