Changing the appointment times that are available

I've set up the appointments for booking of 120 mins as standard. I have two booking slots per day 11-1pm and 2-4pm. I've set this up in thetTime available section.

The result that is displayed is 11am, 1pm and 3pm.

How can I resolve this, so that only the 11am and 2pm time slots are available for the user to select.