UMLR — Inconsistency in constraints and rules for property merge

The constraint #2 (i.e., The value of isUnique of matching Properties must be the same.) demands the values of isUnique for matching properties are the same, which is a prerequisite for merging, but the transformation rule #7 (i.e., For matching Properties: if either the merged and/or receiving elements have isUnique = false, the resulting element has isUnique = false; otherwise, the resulting element has isUnique = true.) ignores it. How to explain it?