from the item on booklium starting issues + answers as copied below – Here another upvote for integration of these calendars.
5. Two calendars, one for checking availability and the other for setting the dates are really clumsy. Just about everyone will futilely click on the availability calendar to set the dates. Even more so on the mobile, because that one is the first one. This should be fixed at all costs. One calendar!
5. Currently this is how the Hotel Booking plugin functions by default. However, we do have such a feature request and are currently collecting our users feedback. In case there are more similar requests from other users, we might consider implementing this feature in one of the plugin future updates.