Hi Marta
Using the new seminar notification the least amount of time before the event is 1 day rather than 1 hour. Both sessions information on the same day can be included in the notification . You could simulate the reminder to be sent on the second event by adding an after event reminder to be sent after the first event for when the second event occurs.
For example if session 2 is 3 days after session 1 then to send a reminder for session 2 1 day before you would add a reminder 2 days after session 1 has finished.
If this isn't suitable then it is possible to enable the old seminar notifications and have both notification systems at the same time.
regards