Does 6.16.2 allow for multiple dimension-default effective arcs as long as they all have the same source and target?
Note that XBRL Dimensions 1.0 specification would require a validation error to be signaled if the targets were different, no matter in which link role they appeared. Furthermore, if the duplicated arcs had the same link role and priority one of them would be ineffectual and thus forbidden by rule 6.9.3.