The practice of maintaining more than one category tree for the same set of items.
Multiple Hierarchies are often created when different parts of an operation have different organizational needs, such as item onboarding vs eCommerce. Maintaining multiple hierarchies requires more active governance and mapping the differences between the hierarchies is a critical. To avoid this, sometimes a single Compromise Hierarchy is created. Some of the same issues with maintaining multiple hierarchies are also seen when managing feeds to third party hierarchies.
Stackonomy, Compromise Hierarchy