Booker25 can handle conflict checking in two different ways.
Shared: Consider all dimension fields/junctions inside a dimension as a single dimension (Default)
Unshared: Consider every dimension field/junctions as separate for conflict checking
You can switch between the behaviors using the Use Shared Conflict Checking checkbox on the Dimension object. The default mode is shared conflict checking, which is recommended for almost all use cases. You should only consider unshared conflict checking if you have a specific use case that requires it.
A clean Booker25 installation will contain a Contact dimension with a dimension field B25__Contact__c and a dimension junction B25__ReservationContact__c. The two distinguish themselves by having two different contact relations to the reservation. For example, you are using this system to create reservations with a primary contact from a customer (dimension field) and a list of guests (dimension junction).
When you use Unsharedconflict checking, considering every dimension field and junction separately, a person can be the guest and the primary contact at the same time. The two reservations will not conflict.
Shared conflict checking, is the best approach for most scenarios. In this case, no matter how the contact is added to the reservation, either as a guest or as an organiser, it would block the contact being booked in another way.
Configuration differences between Shared and Unshared conflict checking
In general, all conflict settings are configured on the Dimension Field (and Junction) level. When shared conflict checking is enabled, the double booking checking strictness is configured at the Dimension level instead. However, the other conflict settings (availability & capacity) still need to be configured at the field & junction level, even if you use shared conflict checking. In that case, you can’t mix a field that uses hard availability checking with a junction that uses soft availability checking. You will get a warning when you try to enable shared conflict checking but not all the conflict checking types are the same.