Using multiple ditavalref elements as the children of a map or map branch indicates that the map or map branch must be conditionally processed using the rules that are specified in the referenced DITAVAL documents.
When multiple ditavalref elements occur as children of the same element, the rules in the referenced DITAVAL documents are processed independently. This effectively requires a processor to maintain one copy of the branch for each ditavalref, so that each copy can be filtered using different conditions.
When a processor maintains multiple copies of a branch for different condition sets, it has to manage situations where a single resource with a single key name results in two distinct resources. Key names must be modified in order to allow references to a specific filtered copy of the resource; without renaming, key references could only be used to refer to a single filtered copy of the resource, chosen by the processor. See Branch filtering: Impact on resource and key names for details on how to manage resource names and key names.