My Regular Users can see the bookings from other user(s) in MultiUser version, after reconfiguration parameters in filter tab. How to fix it ?
Its known issue in the versions 4.0 - 4.0.2 of the Booking Calendar.

For fixing this issue, please open file ../booking/inc/multiuser.php

find this code:

if (! isset($_REQUEST['wh_booking_type'])) {

and replace it to this code:

if ( (! isset($_REQUEST['wh_booking_type'])) || (empty($_REQUEST['wh_booking_type'])) ) {