If you offer multiple different discount codes or bulk booking discounts, the following will happen if a customer tries to use more than one of these at checkout:
Multiple bulk booking discounts
If more than one bulk booking discount is valid for a transaction, the system will automatically apply the better deal to the basket, not all deals.
Multiple discount codes
If a booker has two different valid discount codes and tries to apply both at checkout, the system will automatically decide which discount code gives the booker a better deal and apply only that code. It's not possible to use multiple discount codes when booking on Bookwhen.

Discount code + Bulk booking discount
As in the example above, if a bulk booking discount automatically applies to the basket and the booker adds in a discount code, the system will automatically detect the better deal and only apply that. A customer can't use a bulk booking discount and a discount code simultaneously.

Discounts and Class Passes
If, when making a booking, some tickets are bookable with a class pass, and some are not, the class pass will be redeemed against all valid tickets, and any other discount applies to the remaining tickets in the basket.