It is like a multiple badi implementation: the order doesn't matter. Then nobody know how it is really implemented on the backend 
Multiple Usability for BADI Definitions Multiple use for BADI definitions means that there can be several active BADI implementations. When there is a call, they are all called up - however, in an unpredictable sequence. If you have multiple-use BADI definitions, the sequence must not play any role therefore. A typical example is the execution of checks before a save.