I am using nuget package 17.3.18-beta (not sure how that corresponds to the product version).
When the date of the scheduler is changed, the SelectedDateChanged event fires twice. First with the new date, and second with the date set with the SelectedDate property (or with Today if nothing is set for the SelectedDate property).
The attached sample and images reproduces and show the issue. Once ran, change the date to, for example, November using the datepicker (or by navigating to another month using the keyboard). As shown in the images, the breakpoint at the handler is hit twice, first with the new date (Breakpoint1 and Locals1) and then again with the date set through the SelectedDate property (Breakpoint2 and Locals2). If the SelectedDate property is deleted, the second time it hits with today's date.