In booking types, availability, you can select 'Offer as a multi-session package'. When this is selected clients can book multiple sessions.
When I tested this on the booking page the functionality was confusing. The page opened with already the first available date selected. When the client then goes to the date they want to select it means they have two dates selected and the price for two sessions is shown.
Possible solution;
a) no date should be preselected when opening the booking page for the event
b) it should not be possible to select a second date until a time slot has been selected for the first date.
This way clients will be aware when a date has been selected, and that it needs to be unselected again if they do not wish to book this date.
In it's current form, I won't be able to use the 'Offer as a multi-session package' as I fear that it will confuse my clients and stop them from booking sessions with me.